Botany TermsA

abscisic acid  (ab-siz'ik as'id) (AHA) a growth-inhibiting hormone of plants; it is involved with other hormones in dormancy (p. 203)

abscission  (ab-sizh'un) the separation of leaves, flowers, and fruits from plants after the formation of an abscission zone at the base of their petioles, peduncles, and pedicels (p. 125)

achene  (uh-keen') a single-seeded fruit in which the seed is attached to the pericarp only at its base (p. 140)

acid (as'id) a substance that dissociates in water, releasing hydrogen ions (p. 19)

active transport {ak'tiv trans'port) the expenditure of energy by a cell in moving a substance across a plasma membrane against a diffusion gradient {p. 159)

adventitious  (ad-ven-tish'uss) said of buds developing in internodes or on roots, or of roots developing along stems or on leaves (p. 266)

aerobic respiration (air-oh'bik res-puhray'shun) respiration that requires free oxygen (p. 186)

agar  (ah'gur) a gelatinous substance produced by certain red algae and also a few brown algae; it is often used as a culture medium, particularly for bacteria (p. 199; 341,347)

aggregate fruit  (ag'gruh-git froot) a fruit derived from a single flower having several to many pistils (p. 142)

air layering (air lay'urr-ing) an asexual plant propagation technique whereby aerial stems are induced to form roots. The rooted portion of the stem is then cut and planted (p. 267)

algin  (al'jin) a gelatinous substance produced by certain brown algae; it is used in a wide variety of food substances and in pharmaceutical, industrial, and household products (p. 337)

allele  (uh-leel') one of at least two alternative forms of a gene (p. 242)

Alternation of Generations   ( ol-turnay'shun uv jen-ur-ay'shunz) alternation between a haploid gametophyte phase and a diploid sporophyte phase in the life cycle of sexually reproducing organisms (p. 227,384)

amino acid (ah-mee'noh as'id) one of the organic, nitrogen-containing units from which proteins are synthesized; there are about 20 in all proteins (p. 23)

anaerobic respiration  (an-air-oh'bik respuh-ray'shun) respiration in which the hydrogen removed from the glucose during glycolysis is combined with an organic ion (instead of oxygen) (p. 186)

aneuploid  (an'you-ploid) an aberration in normal chromosome number in which one or more extra chromosomes are present or one or more chromosomes are missing (p. 239)

angiosperm  (an'jee-oh-spurnl) a plant whose seeds develop within ovaries that mature into fruits (p, 442)

annual  (an'you-ul) a plant that completes its entire life cycle in a single growing season(p.91, 132)

annual ring  (an'you-ul ring) a single season's production of xylem (wood) by the vascular cambium (p. 93)

annulus  (an'yu-luss) a specialized layer of cells around a fern sporangium: it aids in spore dispersal through a springlike action; also a membranous ring around the stipe of a mushroom (p. 411 )

anther  (an'thur) the pollen-bearing part of a stamen (p. 133,443)

antheridiophore  (an-thur-id'ee-oh-for) a stalk that bears an antheridium (p. 386)

antheridium  (pl. antheridia) (an-thurid'ee-um: pl. an-thur-id'ee-ah) the male gametangium of certain algae, fungi, bryophytes, and vascular plants other than gymnosperms and angiosperms (p. 332, 351,386)

anthocyanin  (an-thoh-sy'ah-nin) a water-soluble pigment found in cell sap; anthocyanins vary in color from red to blue (p. 43)

antibiotic (an-tee-by-ot'ik) a substance produced by a living organism that interferes with the normal metabolism of another living organism (p. 373)

anticodon (an-tee-koh'don) the three nucleotide sequence in a tRNA molecule that base pairs with the complementary mRNA codon for the amino acid carried by that specific tRNA (p. 237)

apical dominance  (ay'pi-kul dom'i-nunts) suppression of growth of lateral buds by hormones (p. 205)

apical meristem  (ay'pi-kul mair'i-stem) a meristem at the tip of a shoot or root (p.54)

apomixis  (ap-uh-mik'sis) reproduction without fusion of gametes or meiosis in otherwise normal sexual structures (p. 282)

archegoniophore  (ahr-kuh-goh'nee-oh-for) a stalk bearing an archegonium (p. 386)

archegonium  (pi. archegonia) (ahr-kuhgoh'nee-um; pl. ahr-kuh-goh'nee-ah) the multicellular female gametangium of bryophytes and most vascular plants other than angiosperms (p. 386)

aril (air'il) an often brightly colored appendage surrounding the seed of certain plants (e.g., yew) (p. 427)

ascus  (pi. asci) (as'kus; pi. as'eye) one of often numerous, frequently fingerlike hollow structures in which the fusion of two haploid nuclei is followed by meiosis; a row of ascospores (usually eight) is ultimately produced in each ascus on or within the sexually initiated reproductive bodies of cup (sac) fungi (p. 360)

asexual reproduction (ay-seksh'yule reeproh-duk'shun) any form of reproduction not involving the union of gametes (p.222)

assimilation  (uh-sim-i-lay'shun) cellular conversion of raw materials into protoplasm and cell walls (p. 14, 192)

atom (at'um) the smallest individual unit of an element that retains the properties of the element (p. 15)

ATP (ay-tee-pee) adenosine triphosphate. a molecule with three phosphate groups found in all living cells; it is the principal vehicle for energy storage and exchange in cell metabolism (p.173, 176)

autotrophic  (aw-toh-troh'fik) descriptive of an organism capable of sustaining itself through conversion of inorganic substances to organic material (p. 304)

auxin  (awk'sin) a growth-regulating substance produced either naturally by plants or synthetically (p. 200, 266)

axil  (ak'sil) the angle formed between a twig and the petiole of a leaf; normally the site of an axillary bud (also called laleral bud) (p. 87)

B backcross (bak'kross) a cross involving a hybrid and one of

its parents (p. 245) bacteriophage  (bak-teer'ee-oh-fayj) a virus whose host is a

bacterium (p. 319) bark (bahrk) tissues of a woody stem between the vascular

cambium and the exterior (p. 95) base (bayss) a substance that dissociates in water,

relea.5ing hydroxyl (OH-) ions (p. 19, 232) basidiospore  (buh-sidd'ee-oh-spor) a spore produced on

a basidium (p. 367) basidium  (pl. basidia) (buh-sid' ee-um; pi. buh-sid'ee-ah)

one of usually numerous, frequently club-shaped hollow structures in which the fusion of two haploid nuclei is followed by meio5is, the four resulting nuclei becoming e.1(temally borne basidiospores: basidia are produced on or within sexually initiated reproductive bodies of the club fungi (e.g., mushrooms, puffballs) (p. 365, 367)

berry  (bair'ee) a thin-skinned fruit that usually develops from a compound ovary and commonly contains more than one seed (p. 137)

biennial  (by-en'ee-ul) a plant that normally requires two seasons to complete its life cycle, the first season's growth being strictly vegetative (p. 132)

biological controls (by-oh-loj'i-kull kuntrohlz') the use of natural enemies and inhibitors in combating insect pests and other destructive organism5 (p. 542)

biomass (by-oh-ma.5s) the total mass of living organisms present (p. 491)

biome (by'ohm) similar biotic communities considered on a world wide scale (e.g., desert biome, grassland biome) (p.509)

biotechnology (by-oh-tek-nol'-oh-jee) the manipulation of organisms. tissues, cells. or molecules for specific applic[\tions primarily intended for human benefit(p.259-264)

biotic community (by-ot'ik kuh-myu'nitee) an association of plants, animals, and other organisms (e.g., woodland) (p.490)

blade (blayd) the conspicuous, flattened part of a leaf (also called lamina) or seaweed(p.87, 110,337)

bond (bond) a force that holds atoms together (p. 18) bonsai  (bon-sy'J container-grown plants (usually trees) that

have been dwarfed artificially through skillful pruning and manipulation of the growing medium (p.594)

botany (bot'an-ee) science involving the study of plants (p. 7)

botulism (bot'yu-lizm) poisoning from consumption of food infected by botulism bacteria (p. 306)

bract  (brakt) a structure that is usually leaflike and modified in size, shape, or color (p. 121 )

bryophyte  (bry'oh-fyt) a photosynthetic, terrestrial. aquatic, or epiphytic, embryo-producing plant without xylem and phloem (e.g.. mosses, liverworts, hornworts) (p. 382)

budding  a form of asexual reproduction in which a new cell develops to full size from a protuberance arising from a mature cell, as in yeasts (p. 360)

bulb (buhlb) an underground food-storage organ that is essentially a modified bud consisting of fleshy leaves that surround and are attached to a small stem (p. 100,268)

bundle scar  (bun'dul skahr) a small scar left by a vascular bundle within a leaf scar when the leaf separates from its stem through abscission (p. 88)

bundle sheath  (bun'dul sheeth) the parenchyma and/or sclerenchyma cells surrounding a vascular bundle (p. 115)

C callose (kal'ohs) a complex carbohydrate that develops in

sieve tubes following an injury; it is commonly as.5ociated with the sieve areas of sieve tube members (p. 14) callus  (kal'uss) undifferentiated tissue that develops around

injured areas of stems and roots; also the undifferentiated tissue that develops during tissue culture (p.14)

Calvin cycle (kal'vin sy'kuhl) see lightindependent reactions

calyptra (kuh-lip'truh) tissue from the enlarged archegonial wall of many mosses that forms a partial or complete cap over the capsule (p. 387)

calyx  (kay'liks) collective term for the sepals of a flower (p. 132)

cambium  (kam'bee-um) a meristem producing secondary tissues; see va.~cular cambium, cork cambium (p. 54)

capillary water (kap'i-lair-ee waw'tur) water held in the soil against the force of gravity; capillary water is available to plants (p. 81 )

capsule  (kapp'sool) a dry fruit that splits in various ways at maturity, often along or between carpel margins; also the main part of a sporophyte in which different types of tissues develop (p. 140,386)

carbohydrate (kahr-boh-hy'drayt) an organic compound containing carbon, hydrogen, and oxygen. with twice as many hydrogen as oxygen atoms per molecule (p. 21 )

carpel  (kahr'pul) an ovule-bearing unit that is a part of a pistil (p. 133, 136,442)

caryopsis  (kare-ee-op'siss) a dry fruit in which the pericarp is tightly fused to the seed; it does not split at maturity (p.141)

Casparian strip  (kas.5-pair'ee-un strip) a band of suberin around the radial and transverse walls of an endodermal cell (p. 70)

cell (sel) the basic structural and functional unit of living organisms; in plants, it consists of protoplasm surrounded by a cell wall (p. 29)

cell biology (sel by-ol'uh-jee) the biological discipline involving the study of cells and their functions (p. 9)

cell cycle (sel sy'kul) a sequence of events involved in the division of a cell (p.44)

cell division see c.vtokinesis cell membrane (sel mem'brayn) see plasma membrane cell plate (sel playt) the precursor of the middle lamella; it

forms at the equator during telophase (p. 50) cell sap (sel sap) the liquid contents of a vacuole (p. 43) cell wall (sel wawl) the relatively rigid boundary of cells of

plants and certain other organisms (p. 32) central cell nuclei (sen-truhl sell new'kleeeye) nuclei,

frequently two in number, that unite with a sperm in an embryo sac, forming a primary endosperm nucleus (p. 443)

centromere  (sen'truh-meer) the dense, constricted portion of a chromosome to which a spindle fiber is attached (p. 45, 223)

chemiosmosis  (kem-ee-oz-moh'siss) a theory that energy is provided for phosphorylation by protons being "pumped" across inner mitochondrial and thylakoid membranes (p. 190)

chiasma (pi. chiasmata) (kyaz'mah; pi. ky-az'mah-tah) the X-shaped configuration formed by two chromatids

of homologous chromosomes as they remain attached to each other during prophase I of meiosis (p. 223)

chlorenchyma  (klor-en'kuh-mah) tissue composed of parenchyma cells that contain chloroplasts (p. 55)

chlorophyll  (klor'uh-fil) green pigments essential to photosynthesis (p. 41, 175)

chloroplast  (klor'uh-plast) an organelle containing chlorophyll, found in cells of most photosynthetic organisms(p. 40)

chromatid  (kroh'muh-tid) one of the two strands of a chromosome; they are united by a centromere (p. 45, 223)

chromatin  (kroh'muh-tin) a readily staining complex of DNA and proteins found in chromosomes (p. 38)

chromoplast  (kroh'muh-plast) a plastid containing pigments other than chlorophyll; the pigments are usually yellow to orange (p. 41 )

chromosome  (kroh'muh-sohm) a body consisting of a linear sequence of genes and composed of DNA and proteins; chromosomes are found in cell nuclei and appear in contracted form during mitosis and meiosis (p. 38)

cilium (pl. cilia) (sil'ee-um; pl. sil'ee-uh) a short hairlike structure usually found on the cells of unicellular aquatic organisms, normally in large numbers and arranged in rows; the most corrmlon tunction of cilia is propulsion of the cell (p. 213)

circadian rhythm  (sur-kay'dee-an rith'um) a mostly daily rhythm of growth and activity found in living organisms (p. 211 )

citric acid cycle  (sit'rik-ass-id sy'kul) a complex series of reactions following glycolysis in aerobic respiration that involves ATP, mitochondria, and enzymes and that results in the combining of free oxygen with protons and electrons from pyruvic acid to make water (p. 188)

cladistics  (kluh-dis'tiks) analysis of shared features (p. 296) cladophyll  (klad'uh-fil) a flattened stem that resembles a

leaf: also called phylloclade (p. 100) class (klas) a category of classification between a division

and an order (p. 289, 290) climax vegetation (kly'rnaks vej-uhtay'shun) vegetational

association that perpetuates itself indefinitely at the culmination of ecological succession (p. 499)

cloning vector (kloh'ning vek'torr) a DNA molecule that can replicate and transfer DNA between cells (p. 260)

codon (koh'donn) the sequence of three nucleotides in an mRNA molecule that constitutes the code for a specific amino acid or a stop signal in protein synthesis; it is complementary to an anticodon (p.233)

coenocytic (see'-no-sitt-ik) multinucleate, the nuclei not individually separated from one another by crosswalls, as in the hyphae of water molds (p. 357)

cohesion-tension theory (koh-hee'zhun ten'shun thee'uh-ree) theory that explains the rise of water in plants through a combination of cohesion of water molecules in vessels and tracheids and tension on the water columns brought about by transpiration (p. 161)

coleoptile  (koh-lee-op'tul) a protective sheath surrounding the emerging shoot of seedlings of the Grass Family (Poaceae) (e.g., corn, wheat) (p. 148)

coleorhiza  (koh-lee-uh-ry'zuh) a protective sheath surrounding the emerging radicle (immature root) of members of the Grass Family (Poaceae) (e.g., corn, wheat) (p. 148)

collenchyma  (kuh-len'kuh-rnuh) tissue composed of cells with unevenly thickened walls (p. 55)

colloid   (kol'oyd) a substance consisting of a medium in which fine particles are permanently dispersed (p. 81)

community (kuh-myu'nit-ee) a collective tern for all the living organisms sharing a common environment and interacting with one another (p. 491 )

companion cell  (kum-pan'yun sel) a specialized cell derived from the same parent cell as the closely associated sieve tube member immediately adjacent to it (in angiosperm phloem) (p. 60)

compost (kom'post) a mixture of decomposed organic matter, particularly decomposed plant materials (p. 305)

compound (kom'pownd) a substance \\.hose molecules are composed of two or more elements (p. 17)

compound leaf (kom'pownd leef)a leaf whose blade is divided into distinct leaflets (p. I 10)

conidium (pl. conidia) (kuh-nid'ee-um: pl. kuh-nid'ee-uh) an asexually produced fungal spore formed outside of a sporangium (p. 360)

conifer (kon'i-fur) a cone-bearing tree or shrub (p. 423) conjugation (kon-juh-gay'shun) a process leading to the

fusion of isogametes in algae, fungi, and protozoa; also the means by which certain bacteria exchange DNA (p. 331 )

conjugation tube  (kon-juh-gay'shun t(y)oob) a tube permitting transfer of a game1e or gametes between adjacent cells, as in Spirogyra or desmids (p. 331 )

consumer (kon-soo'muhr) organisms that feed on producers (p. 492)

cork (kork) tissue composed of cells whose walls are impregnated with suberin at maturity; the outer layer of tissue of an older woody stem: produced by the cork cambium (p. 62)

cork cambium  (kork kam'bee-um) a narrow cylindrical sheath of cells between the exterior of a woody root or stem and the central vascular tissue: it produces cork to its exterior and phelloderm to its interior: it is also called phellogen (p. 55, 90)

corm  (korm) a vertically oriented, thickened food-storage stem that is usually enveloped by a few papery nonfunctional leaves (p. 100)

corolla   (kuh-rahl'uh) collective term for the petals ofa flower(p. 132)

cortex  (kor'teks) a primary tissue composed mainly of parenchyma: the tissue usually extends between the epidermis and the vascular tissue (p. 70, 88)

cotyledon  (kot-uh-lee'dun) an embryo leaf ("seed leaf') that usually either stores or absorbs food (p. 91,147)

covalent  bond (koh-vay'luhnt bond) a force provided by pairs of electrons that travel between two or more atomic nuclei: holding atoms together and keeping them at a stable distance from eachother(p.18)

crossing-over  (kross'ing oh'vur) the exchange of corresponding segments of chromatids between homologous chromosomes during prophase I of meiosis (p.223)

crown division (krown duh-vizh'unn) the asexual production of multiple plants by division of the base of a stem (crown) (p. 266)

cuticle (kyut'i-kul) a waxy or fatty layer of var)'ing thickness on the outer walls of epidermal cells (p. 60, 112)

cutin (kyu'tin) the waxy or fatty substance of which a cuticle is composed (p. 60, 112)

cutting (kutt'ing) any vegetative plant part used for asexual propagation (p. 266)

cyclosis (sy-kloh'sis) the flowing or streaming of cytoplasm within a cell (p.44)

cytochrome  {sy'toh-krohm) iron containing protein involved in molecule transfer in an electron transport system (p. 180)

cytogenetics  (sy'toh-juh-net-iks) the study of the genetic effects of chromosome structure and behavior {p. 239)

cytokinesis (sy-toh-kuh-nee'sis) division of a cell, usually following mitosis (p.45)

cytokinin  (syt-uh-ky'nin) a growth hormone involved in cell division and several other metabolic activities of cells {p. 203)

cytology {sy-tol'uh-jee) see cell biology g'toplasm {sy'tuh-plazm) the protoplasm of a cell exclusive of the nucleus {p. 32)

cytoplasmic streaming {sy-tuh-pJaz'mik streem'ing) see cyclosis

cytoskeleton  (sy-toh-skel'uh-ton) a network of microtubules and microfilaments involved in movement within a cell (p. 44)

cytosol  (sy'toh-sol) fluid. living part of a cell; organelles are distributed within it (p. 32)

D dark reactions (dahrk ree-ak'shunz) see light-independent

reactions day-neutral plant (day new'trul plant) a plant that is not

dependent on specific day lengths for the initiation offlowering (p. 215)

deciduous  (duh-sij'yu-wuss) shedding leaves annually (p. 88, 110,125)

decomposer  {dee-kuhm-poh'zur) organism {e.g., bacterium, fungus) that breaks down organic material to forms capable of being recycled {p. 492)

dedifferentiate (dee-diff-urr-en'shee-ayt) to become less specialized (usually pertains to cells) (p. 266)

development (duh-vel'up-ment) changes in the form of a plant resulting from growth and differentiation of its cells into tissues and organs (p. 198)

dicotyledon  (dy-kot-uh-lee'dun) a class of angiosperms whose seeds commonly have two cotyledons; frequently abbreviated to dicot (p. 91 )

dictyosome (dik'tee-oh-sohm) an organelle consisting of disc-shaped, often branching hollow tubules that function in accumulating and packaging substances used In the synthesis of materials by the cell (p. 40)

differentially permeable membrane   (difuh-rensh'uh-lee pur'mee-uh-bul mem'brayn) a membrane through which different substances diffuse at different rates (p. 156)

differentiation   ( dif-uh-ren-shee-ay' shun) the change of a relatively unspecialized cell to a more specialized one (e.g., the change of a cell just produced by a meristem to a vessel member or fiber) (p. 198)

diffusion  (dif-fyu'zhin) the random movement of molecules or particles from a region of higher concentration to a region of lower concentration, ultimately resulting in unifolm distribution (p. 156)

digestion (duh-jes'jinJ an enzymecontrolled conversion of complex. usually insoluble substances to simpler, usually soluble substances (p. 14, 192)

dihybrid cross  (dy-hy'brid kross) a cross involving two different pairs of genes and heterozygous parents (p. 245)

dikaryotic  (dy-kair-ee-ot'ik) having a pair of nuclei in each cell or a type of the mycelium in club fungi (p. 366)

dioecious  (dy-ee'shuss) having unisexual flowers or cones. with the male flowers or cones confined to certain plants and the female flowers or cones of the same species confined to other different plants (p. 450)

diploid   (dip'loyd) having two sets of chromosomes in each cell; the 2n chromosome number characteristic of the sporophyte generation (p. 226)

disinfest (diss'in-fest) the removing of surface contaminants from a plant surface (p. 269)

diuretic  (dy-yu-ret'ik) a substance tending to increase the flow of urine (p. 409)

division (duh-vizh'un) the largest undivided category ofclassification of organisms within a kingdom; considered synonymous with phylum (p. 290)

DNA (dee-en-ay) standard abbreviation of deoxyribonucleic acid, the carrier of genetic information in cells and viruses (p.26)

dominance  (dom'uh-nints) a condition in which one allele of a gene (dominant allele) masks the phenotypic expression of another allele (recessive allele) (p.242)

dormancy  (dor'man-see) a period of growth inactivity in seeds, buds, bulbs, and other plant organs even when environmental conditions normally required for growth are met (p.148,217)

double fusion  (dub'ul fu'shun) the more or less simultaneous union of one sperm and egg (forming a zygote) and union of another sperm and central cell nuclei (forming a primary endosperm nucleus) that occur in the megagametophyte of flowering plants (p.447)

drupe  (droop) a simple fleshy fruit whose single seed is enclosed within a hard endocarp (p. 137)

E ecology (ee-kol'uh-jee) the biological discipline involving

the study of the relationships of organisms to each other and to their environment (p. 488)

ecosystem  (ee'koh-sis-tim) a system involving interactions of living organisms with one another and with their nonliving environment (p. 490)

egg (eg) a nonmotile female gamete elater (el'uh-tur) a straplike appendage (usually occurring in

pairs) attached to a horsetail (Equisetum) spore (p. 407); also, a somewhat spindle-shaped sterile cell occurring in large numbers in liverwort sporangia (p. 387); both types of elaters facilitate spore dispersal

electron (ee-lek'tron) a negatively charged particle ofan atom (p. 15)

element (el'uh-mint) one of more than 100 types of matter, most existing naturally but some human-made, each of which is composed of one kind of atom (p. 15)

embryo (em'bree-oh) immature sporophyte that develops from a zygote within an ovule or archegonium after fertilization (p.66, 382, 386, 426)

enation (ee-nay'shun) one of the tiny, green leaflike outgrowths on the stems of whisk ferns (Psilotum) (p.398)

endocarp  (en'doh-kahrp) the innermost layer of a fruit wall (p. 136)

endodermis  (en-doh-dur'mis) a single layer of cells surrounding the vascular tissue (stele) in roots and some stems; the cells have Casparian strips (p.70)

endoplasmic reticulum  (en-doh-plaz'mik ruh-tik'yu-lum) a complex system of interlinked double-membrane channels subdividing the cytoplasm of a cell into compartments; parts of it are lined with ribosomes (p. 38)

endosperm  (en'doh-spurm) a food-storage tissue that develops through divisions of the primary endosperm nucleus; it is digested by the sporophyte after germination in some species (e.g., com) or before maturation of the seed in other species (e.g.. beans) (p. 448)

endosymbiont hypothesis  (en-dohsim'bee-ont hy-poth'uh-sis) the theory that mitochondria and chloroplasts were free-living bacteria that became incorporated in cells. (p. 248)

energy (en'ur-jee) the capacity to do work; some forms of energy are heat, light. and kinetic (p. 20)

enzyme  (en'zym) one of numerous complex proteins that speeds up a chemical reaction in living cells without being used up in the reaction (i.e.. it catalyzes the reaction) (p.24, 174.233)

epicotyl   (ep'uh-kaht-ul) the part of an embryo or seedling above the attachment point of the cotyledon(s) (p. 148)

epidermis   (ep-uh-dur'mis) the exterior tissue, usually one cell thick. of leaves, young stems and roots. and other parts of plants (p. 60)

epigynous( ee-pidj'uh-nuss ) having flower parts attached above the ovary (p. 449)

epiphyte  (ep'uh-fyt) an organism that is attached to and grows on another organism without parasitizing it (p.326)

ergotism (ur'got-izm) a disease resulting from consumption of goods made with flour containing ergot fungus (p. 361 )

essential element (eh-sen'shul e\'uh-mint) one of 18 elements generally considered essential to the normal growth, development. and reproduction of most plants (p. 166)

ethylene   (eth'uh-leen) a simple. naturally produced. gaseous hormone that inhibits plant growth and promotes the ripening of fruit (p. 204 )

etiolation   (ee-tee-oh-lay'shun) a condition characterized by long internodes. poor leaf development. and pale, weak appearance due to a plant's having been deprived of light (p. 215)

eukaryotic  (yu-kair-ee-ot'ik) pertaining to cells having distinct membrane-bound organelles, including a nucleus with chromosomes (p. 32)

eutrophication   (yu-troh-fuh-kay'shun) the gradual enrichment of a body of water through the accumulation of nutrients. resulting in a corresponding increase in algae and other organisms (p.501)

evolution (ev-oh-loo'shun) the accumulation of genetic changes in populations of living organisms through many generations (p. 274)

exine (ek'syne) the outer layer of the wall of a pollen grain or spore (p. 444)

exocarp  (ek'soh-kahrp) the outermost layer of a fruit wall (p. 135)

explant (eks'plant) an excised portion of leaf or stem tissue used for tissue culture (p. 269)

extranuclear DNA (ex-truh-nyu'klee-ahr dee-en'ay) DNA found outside the nucleus, typically in plastids and mitochondria (p. 248)

eyespot (eye'spot) a small. often reddish structure within a motile unicellular organism; it appears to be sensitive to light (also called stigma) (p. 341 )

F F 1 (first filial generation) (eff wun) the offspring of a cross

between two parent plants (p. 242) F 2 (second filial generation) (efftoo) the offspring of the

F1 generation (p. 242) FAD  (eff-ay-dee) flavin adenine dinucleotide, a hydrogen

acceptor molecule involved in the Krebs cycle of respiratjon and in photosynthesis (p. 180)

family (famm'uh-lee) a classification category between genus and order (p. 290)

fat (fat) an organic compound containing carbon. hydrogen. and oxygen but with proportionately much less oxygen than is present in a carbohydrate molecule (p. 22)

fermentation  (fur-men-tay'shun) respiration in which the hydrogen removed from the glucose during glycolysis is transferred back to pyruvic acid. creating substances such as ethyl alcohol or lactic acid (p. 186)

fertilization  (fur-til-i-zay'shun) formation of a zygote through the fusion of two gametes (p. 228, 447)

fiber  (fy'bur) a long thick-walled cell whose protoplasm often is dead at maturity (p. 55)

filament  (fil'uh-mint) threadlike body of certain bacteria, algae, and fungi (p. 301); also the stalk portion of a stamen (p. 133)

fission  (fish'un) the division of cells ofbacteria and related organisms into two new cells (p. 301,302)

flagellum  (pi. flagella) (fluh-jel'um; pl. fluh-jel'uh) a fine threadlike structure protruding from a motile unicellular organism or the motile cells produced by multicellular organisms; functions primarily in locomotion (p. 213, 301)

floret  (flor'et) a small flower that is a part of the inflorescence of members of the Sunflower Family (Asteraceae) and the Grass Family (Poaceae) (p. 479)

florigen (ftor'uh-jen) one or more hormones once thought from circumstantial evidence to initiate ftowering but which have never been isolated or proved to exist (p. 2 16)

follicle  (folJ'uh-kuhl) a dry fruit that splits along one side only (p. 138)

food chain (food chayn) a natural chain of organisms of a community wherein each member of the chain feeds on members below it and is consumed by members above it, with autotrophic organisms (producers)being at the bottom; interconnected food chains are referred to asfood webs (p. 492)

foot (foot) the basal part of the embryo of bryophytes and other plants; it is attached to and absorbs food from the gametophyte (p. 386)

fossil (fos'ul) the remains or impressions of any natura] object that has been preserved in the earth's crust (p. 4 I 7)

frond  (frond) a fern leaf; term occasionally also applied to palm leaves (p. 410)

fruit (froot) a mature ovary usually containing seeds: term also somewhat loosely applied to the reproductive structures of grours of plants other than angiosperms ( p. 134)

fucoxanthin (fyu-koh-zan'thin) a brownish pigment occulTing in brown and other algae (p. 334,337)

G gametangium  (pi. gametangia) (gam-uhtan'jee-um; pi. gam-

uh-tan'jee-ah) any cell or structure in which gametes are produced (p. 338, 382)

gamete  (gam'eet) a sex cell; one of two cells that unite, forming a zygote (p. 222)

gametophore  (guh-me'toh-for) a stalk on which a gametangium is borne (p. 386)

gametophyte  (guh-me'toh-fyte) the haploid (n) gamete-producing phase of the life cycle of an organism that exhibits Alternation of Generations (p. 227)

gemma  (pl. gemmae) (jem'uh; pl. jem'ee) a small outgrowth of tissue that becomes detached from the parent body and is capable of developing into a complete new plant or other organism; gemmae are produced in cuplike structures on liverwort thalli and are also produced by certain fungi (p. 386)

gene (jeen) a unit of heredity; part of a linear sequence of such units occurring in the DNA of chromosomes (p. 26, 233)

gene bank (jeen bank) a collection of plants or seeds maintained for their germ plasm (p. 259)

generative cell  (jen'uh-ray-tiv sel) the cell of the male gametophyte of angiosperms that divides, producing two sperms; also, the cell of the male gametophyte of gymnosperms that divides, producing a sterile cell and a spermatogenous cell (p. 426) 

gene synthesizer (jeen sin'thuh-size-ua) a machine that creates specific DNA sequences (p. 260)

genetic drift  (juh-net'ik drift) a change in the genetic makeup of a population that may take place by chance alone (p.278)

genetic engineering  (juh'net'ik en-juhneer'ing) the introduction, by artificial means. of genes from one form of DNA into another form of DNA (p. 259)

genetics (juh-net'iks) the biological discipline involving the study of heredity (p.9)

genome  (jee'nohm) the sum total of DNA in an organism's chromosomes (p. 233)

genotype  (jecn'oh-typ) the genetic constitution of an organism; mayor may not be visibly expressed, as contrasted with phenotype (p. 242)

genus (pl. genera) (jee'nus; pl. jen'er-ah) a category of classification between a family and a species (p. 288)

germination   (jur'min-ay-shun) the beginning or resumption of growth of a seed or spore (p. 148)

germ-line mutation (jurm'-lyn mewtay'shun) a mutation in a cell from which gametes are derived; the mutation can be passed on to offspring (p, 238)

germ plasm  (jurm plaz'im) the sum total of all the genes of a species or group of organisms (p. 258)

gibberellin  (jib-uh-rel'in) one of a group of plant hormones that have a variety of effects on growth; they are particularly known for promoting elongation of stems (p. 202)

gill (gil) one of the flattened plates of compact mycelium that radiate out from the stalk on the underside of the caps of most mushrooms (p. 367)

girdling  (gurd'ling) the removal of a band of tissues extending inward to the vascular cambium on the stem of a woody plant (p. 267)

gland (gland) a small body of variable shape and size that may secrete certain substances but that

also may be functionless (p. 61, 113) glycolysis  (gly-kol'uh-sis) the initial phase of all types of

respiration in which glucose is converted to pyruvic acid without involving free oxygen (p. 186)

graft  (graft) the union of a segment of a plant, the scion, V.'ith a rooted portion, the stock (p. 267)

grain  (grayn) see caryopsis granum  (pl. grana) (granum; pl. granuh) a series of stacked

thylakoids within a chloroplast (p. 40) gravitational water (grav-uh-tay'shun-ul waw'tur) water that

drains out of the pore spaces of a soil after a rain (p. 81 ) gravitropism (grav-uh-troh'pism) growth response to

gravity (p. 208) ground meristem  (grownd mair'i-stem) meristem that

produces all the primary tissues other than the epidermis and stele (e.g., cortex, pith) (p. 54, 68, 88)

growth (grohth) progressive increase in size and volume through natural deve1opment (p. 13)

guard cell  (gahrd sel) one of a pair of specialized cells surrounding a stoma (p. 61,114)

guttation  (guh-tay'shun) the exudation from leaves of water in liquid form due to root pressure (p. 110, 164)

gymnosperm  (jimnoh-spurm) a plant whose seeds are not enclosed within an ovary during their development (e.g., pine tree) (p. 422)

H half-life (haf-lyf) the amount of time it takes for a

radioactive element to lose half of its radioactivity (p. 276) haploid  (hap'loyd) having one set of chromosomes per cell,

as in gametophytes; also referred to as having II chromosomes (as contrasted with 211 chromosomes in the diploid cells of sporophytes) (p. 226)

haustorium  (pi. haustoria) (haw-stor'eeurn; pl. haw-stor'ee-uh) a protuberance of a fungal hypha or plant organ such as a root that functions as a penetrating and absorbing structure (p. 75)

heartwood  (hahrt'wood) nonliving, usually darker-colored wood whose cells have ceased to function in water conduction (p. 94)

heirloom variety (air'loom vuh-rye'it-ee) a previously popular plant variety that is c1,1rrently being maintained because of certain desirable qualities (p. 258)

herbaceous (hur-bay'shuss or ur-bay'shuss) referring to nonwoody plants (p. 91 )

herbarium (pl. herbaria) (hur-bair'ee-urn or ur-bair'ee-um; pi. hur-bair'ee-uh) a collection of dried pressed specimens, usually mounted on paper and provided with a label that gives collection information and an identification (p. 453)

heterocyst  (het'uh-roh-sist) a transparent, thick-walled, slightly enlarged cell occurring in the filaments of certain cyanobacteria (p. 313)

heterosis (hett-urr-oh'sis) hybrid vigor; superior qualities of heterozygous off spring as compared with those of their homozygous parents (p. 258)

heterospory (het-uh-ross'por-ee) the production of both microspores and megaspores (p. 401)

heterotrophic  (het-ur-oh-troh'fick) incapable of synthesizing food and therefore dependent on other organisms for it (p. 304)

heterozygous  (het-uh-roh-zy'guss) having two different alleles at the same locus on homologous chromosomes (p. 243, 257)

hold fast  (ho1d'fast) attachment organ or cell at the base of the thallus or filament of certain algae (p. 329, 337)

homologous chromosomes  (hoh-mol'uhguss kroh'muh-sohmz) pairs of chromosomes that associate together in prophase I of meiosis; each member of a pair is derived from a different parent (p. 223)

homozygous  (hoh-moh-zy'guss) having two identical alleles at the same locus on a pair of homologous chromosomes (p. 243, 256)

hormone  (hor'mohn) an organic substance generally produced in minute amounts in one part of an organism and transported to another part of the organism where it controls or affects growth and development (p. 199)

hybrid  (hy'brid) heterozygous offspring of two parents that differ in one or more inheritable characteristics (p. 244, 258, 281)

hydathode (hy'duh-thohde) structure at the tip of a leaf vein through which water is forced by root pressures (p. 164)

hydrolysis (hy-drol'uh-sis) the breakdown of complex molecules to simpler ones as a result of the union of water with the compound; the process is usually controlled by enzymes (p. 192)

hydrosere (hy'droh-sear) a primary succession that is initiated in a wet habitat (p. 499)

hygroscopic water (hy-gruh-skop'ik waw'tur) water that is chemically bound to soil particles and therefore unavailable to plants (p. 81 )

hypha   (pi. hyphae) (hy'fuh; pi. hy'fee) a single, usually tubular, threadlike filament of a fungus; mycelium is a collective term for hyphae (p. 356)

hypocotyl  (hy-poh-kot'ul) the portion of an embryo or seedling between the radicle and the cotyledon(s) (p. 148)

hypodermis  (hy-poh-dur'mis) a layer of cells immediately beneath the epidermis and distinct from the parenchyma cells of the cortex in certain plants (p. 118,422)

hypogynous   (hi-podj'un-nuss) having flower parts attached below the ovary (p. 449)

hypothesis  (hy-poth'uh-sis) a postulated explanation for some observed facts that must be tested experimentally before it can be accepted as valid or discarded if it proves to be incorrect (p.7)

I imbibition  (im-buh-bish'un) adsorption of water and

subsequent swelling of organic materials because of the adhesion of the water molecules to the internal surfaces (p. 157)

inbreeding  (in'breed-ing) mating between individuals with a common ancestry (p.256)

inbreeding depression (in'breed-ing deepresh'unn) poor performance and low fertility of inbred individuals (p.258)

incomplete dominance  (in'kom-pleet dom'in-uns) a condition in which the heterozygous phenotype is intermediate to the two homozygous phenotypes as a result of one allele only partly masking another allele (p. 247)

indusium  (plo indusia) (in-dew'zee-um; pl. in-dew'zee-uh) the small, membranous, sometimes umbrellalike covering of a developing fern sorus (p. 411 )

inferior ovary (in-feer'ee-or oh'vuh-ree) an ovary to which parts of the calyx, corolla, and stamens have become more or less united so they appear to be attached at the top of it (p. 133, 449)

inflorescence   (in-fluh-res'ints) a collective term for a group of flowers attached to a common axis in a specific arrangement (p. 133)

inorganic (in-or-gan'ik) descriptive of compounds having no carbon atoms (p. 21)

integument (in-teg'yu-mint) the outermost layer of an ovule; usually develops into a seed coat; a gymnosperm ovule usually has a single integument, and an angiosperm ovule usually has two integuments (p. 422, 426, 443)

intermediate-day plant (in-tur-me'dee-ut day plant) a plant that has two critical photoperiods; it will not flower if the days are either too short or too long (p.214)

internode  (in'tur-nohd) a stem region between nodes (p. 87, 110)

inversion (chromosomal) (in-verzh'un) a chromosome rearrangement as a result of a segment having been removed, rotated 1800, and then reinserted (p.239)

in vitro (in vee'troh) "in glass"; growing or being maintained on artificial media, usually in glass test tubes or flasks (p.269)

ion (eye'on) a molecule or atom that has become electrically charged through the loss or gain of one or more electrons (p.18)

isogamy  (eye-sog'uh-me) sexual reproduction in certain algae and fungi having gametes that are alike in size (p. 330)

isotope (eye'suh-tohp) one of two or more forms of an element that have the same chemical properties but differ in the number of neutrons in the nuclei of their atoms (p. 16)

K kinetochore  (kuh-net'uh-kor) specialized protein complexes

that develop on the vertical faces of a centromere during late prophase; spindle fibers are attached to them (p. 45)

kingdom (king'dum) the highest category of classification (e.g., Plant Kingdom, Animal Kingdom) (p. 290)

knot (not) a portion of the base of a branch enclosed within wood (p. 104)

L lamina   (lam'uh-nuh) see blade lateral bud (lat'uh-rul bud) see axil laticifer (luh-tis'uh-fur) specialized cells or ducts

resembling vessels; they form branched networks of latex-secreting cells in the phloem and other parts of plants (p. 97)

leaf   (leef) a flattened, usually photosynthetic structure arranged in various ways on a stem (p. 110)

leaf gap  (leef gap) a parenchyma-filled interruption in a stem's cylinder of vascular tissue immediately above the point at which a branch of vascular tissue (leaf trace) leading to a leaf occurs {p. 90)

leaflet  (leef'Jit) one of the subdivision, of a compound leaf (p. 110)

leaf scar  (leef skahr) the suberin-covered scar left on a twig when a leaf separates from it through abscission (p. 88)

leaf trace  (leeftrays) see leafgap legume  Oeg'yoom) a dry fruit that splits along two "seams,"

the seeds being attached along the edges (p. 138) lenticel  (lent'uh-sel) one of usually numerous, slightly

raised, somewhat spongy groups of cells in the bark of woody plants; lenticels permit gas exchange between the interior of a plant and the external atmosphere (p. 62, 90)

leucoplast  (loo'kuh-plast) a colorless plastid commonly associated with starch accumulation (p. 41)

light-dependent reactions (lyt-dee-pendent ree-ak'shunz) a series of chemical and physical reactions through which light energy is converted to chemical energy with the aid of chlorophyll molecules; in the process, water molecules are split, with hydrogen ions and electrons being produced and oxygen gas being released: ATP and NADPH also are created (p. 176)

light-independent reactions (lyt in-deepen-dent ree-ak'shunz) a cyclical series of chemical reactions that utilizes cal-bon dioxide and energy generated during the light-dependent reactions of photosynthesis. producing sugars, some of which are stored as insoluble carbohydrates, while others are recycled: the reactions are independent of light and occur in the stroma of chloroplasts(p. 176)

lignin  (lig'nin) a polymer with which certain cell walls (e.g., those of wood) become impregnated (p. 55 )

ligule (lig'yool) the tiny tongue-like appendage at the base of a spike moss (Selaginella) or quillwort (Isoetes) leaf (p. 401)

linked genes ( linked jeens ) genes located on the same chromosome (p. 245.248)

lipid (lip'id) a general term for fats, fatty substances, and oils (p. 22)

locule (lok'yool) a cavity within an ovary or a sporangium (p. 140)

locus  (loh'kuss) the position of a gene on a chromosome (p. 242.249)

long-day plant (long-day plant) a plant in which flowering is not initialed unless exposure to more than a critical day length occurs (p. 214)

M

map unit (map you'nit) a unit of measure equivalent to 1% recombination (p. 249)

mass-flow hypothesis (mass flo hy-poth' uh-sus) see pressure-flow hypothesis

mass selection (mass suh-lek'shun) a plant breeding technique in which seeds of plants in a population are used to create each generation (p. 257)

maternal inheritance (muh-terr'nal inhair'it-ans) inheritance in which the female gamete contributes extranuclear genes to Tle offspring (p. 248)

megagametophyte  (meg-uh-ga-mee'tohfyt) the female gametophyte of angiosperms, which, in approximately 70% of the species investigaled, 'contains eight nuclei (p. 443)

megaphyll  (meg'uh-fill) a leaf having branching veins: it is associated with a leaf gap (p. 410)

megasporangium  (meg-uh-spor'an-jeeurn) a sporangium in which megaspores are formed (p. 425)

megaspore  (meg'uh-spor) a spore that develops into a female gamelophyte (megagametophyte) (p. 401,425, 443)

megasporocyte  (meg uh-spor'oh-syt) a diploid cell that produces megaspores upon undergoing meiosis (p. 401, 426, 443)

meiocyte (my'oh-syt) see sporocyte meiosis  (my-oh'sis) the process of two successive nuclear

divisions through which segregation of genes occurs and a single diploid (2/1) cell becomes four haploid (/1) cells (p. 222)

mericloning (mair'i-kloh-ning) see micropropagation meristem  (mair'i-stem) a region ofundifferentiated cells in

which new cells arise (p. 54) mesocarp  (mez'uh-karp ) the middle region of the fruit wall

that lies between the exocarp and the endocarp (p. 136) mesophyll  (mez'uh-fil) parenchyma (chlorenchyma) tissue

between the upper and lower epidermis of a leaf (p.115.397)

metabolism  (muh-tab'uh-lizm) the sum of all the interrelated chemical processes occurring in a living organism (p. 171)

microfilament  (my'kroh-fil'uh-mint) a protein filament involved with cytoplasmic streaming and with contraction and movement in eukaryotic cells (p. 44)

microphyll  (my'kroh-fil) a leaf having a single unbranched vein not associated with a leaf gap (p. 397)

micropropagation  (my-kroh-prop-uhgay'shun) propagation of plants in vitro (p. 269)

micropyle  (my'kroh-pyl) a pore or opening in the integuments of an ovule through which a polleQtube gains access to an e'11bryo sac or archegonium of a seed plant (p. 426.443)

microshoot (my'kroh-shoot) one of several to many shoots produced by a plant growing in vitro (p. 270)

microsporangium  (my-kro-spor-anj'eeurn) a sporangium in which microspores are formed (p. 425)

microspore  (my'kroh-spor) a spore that develops into a male gametophyte (microsporocyte) (p. 401,443)

microsporocyte  (my'kroh-spor'oh-syt) a diploid cell that produces microspores upon undergoing meiosis (p. 401, 425, 443)

microsporophyll  (my-kroh-spor'uh-fil) a leaf, usually reduced in size, on or within which microspores are produced (p.401)

microtubule  (my'kroh-t(y)oo-byul) an unbranched tubelike proteinaceous structure commonly found inside the plasma membrane where it apparently regulates the addition of cellulose to the cell wall (p.44)

middle lamella  (mid'ulluh-mel'uh) a layer of material. rich in pectin. that cements two adjacent cell walls together (p. 35)

midrib (rnid'rib) the central (main) vein of a pinnately veined leaf or leaflet (p. 112) mitochondrion (pl. mitochondria) (my toh-kon'dree-un; pl. my-toh-kon'dreeuh) an organelle containing enzymes that function in the citric acid cycle and the electron transport chain of aerobic respiration (p. 42)

mitosis  (my-toh'sis) nuclear division, usually accompanied by cytokinesis. during which the chromatids of the chromosomes separate and two genetically identical daughter nuclei are produced (p. 44)

molecule (mol'uh-kyul) the smallest unit of an element or compound retaining its own identity; consists of two or more atoms(p.14, 17)

monocotyledon  (mon-oh-kot-uh-lee'dun) a class of angiosperms whose seeds have a single cotyledon; commonly abbreviated to monocot (p. 91)

monoecious  (moh-nee'shuss) having unisexual male flowers or cones and unisexual female flowers or cones both on the same plant (p. 450)

monohybrid cross  (mon-oh-hy'brid kross) a cross involving a single pair of genes and heterozygous parents (p. 244)

monokaryotic (mon-oh-kair-ee-ot'ik) having a single nucleus in each cell or unit of the mycelium in club tungi (p. 366)

monomer  (mon'oh-mur) a simple individual molecular unit of a polymer (p. 21 )

motile (moh'tul) capable of independent movement(p.301) multiple fruit  (mul'tuh-pul froot) a fruit derived from

several to many individual flowers in a single inflorescence (p. 142)

mushroom (mush'room) a sexually initiated phase in the life cycle of a club fungus. usually consisting of an expanded cap and a stalk ( stipe ) (p. 366)

mutagen  (mew'tuh-jenn) an agent that causes a mutation to occur (p. 238)

mutation  (myu-tay'shun) a heritable change in a gene or chromosome (p. 238)

mycelium  (my-see'lee-um) a mass of fungal hyphae (p. 356)

mycorrhiza  (pl. mycorrhizae) (my-kuhry'zuh; pi. my-kuh-ry'zee) a symbiotic association between fungal hyphae and a plant root (p. 75)

N n (en) having one set of chromosomes per cell (haploid) (p.

226) NAD   (en-ay-dee) nicotinamide adenine dinucleotide. a

molecule that during respiration temporarily accepts electrons whose negative charges are balanced by also accepting protons and thereby hydrogen atoms (p.188)

NADP  (en-ay-dee-pee)nicotinamide adenine dinucleotide phosphate, a high energy storage molecule that temporarily accepts electrons from photosystern I in the light reactions of photosynthesis (p. 176, 180)

nastic movement (nass'tik moov'rnint) a nondirected movement of a flat organ (e.g., petal, leaf) in which the organ alternately bends up and down (p.207)

neutron (new'tron) an uncharged particle in the nucleus of an atom (p.15)

node  (nohd) region of a stem where one or more leaves are attached (p.55, 87)

noncoding DNA (non-koh'ding dee-en-ay) DNA that does not code for a gene (p. 237)

nucellus (new-se\'us) ovule tissue within which an embryo sac develops (p.422, 426)

nuclear envelope (new'klee-ur en'vuhlohp) a porous double membrane enclosing a nucleus (p. 37)

nucleic acid (new-klay'ik as'id) see DNA, RNA nucleolus (pl. nucleoli) (new-klee'oh-luss; pl. new-klee'oh-

ly) a somewhat spherical body within a nucleus; contains primarily RNA and protein; there may be more than one nucleolus per nucleus (p.38)

nucleotide  (new'klee-oh-tyd) the structural unit of DNA and RNA (p.26, 232)

nucleus (new'klee-uss) the organelle of a living cell that contains chromosomes and is essential to the regulation and control of all the cell's functions; also, the core of an atom (p.15, 37)

nut (nutt) one-seeded dry fruit with a hard, thick pericarp; a nut develops with a cup or cluster of bracts at the base (p. 140)

nutrient (noo'tree-uhnt) a substance that furnishes the elements and energy for the organic molecules that are the building blocks from which an organism develops (p. 198)

O oil (oyl) a fat in a liquid state (p. 22) oogamy  (oh-og'uh-mee) sexual reproduction in which the

female gamete, or egg, is nonmotile and larger than the male gamete, or sperm, which is motile (p.332)

oogonium  (pi. oogonia) (oh-oh-goh'neeurn; plo oh-oh-goh'nee-ah) a female sex organ of certain algae and fungi; it consists of a single cell that contains one to several eggs (p. 332, 351 )

operculum  (oh-per'kyu-lum) the lid or cap that protects the peristome of a moss sporangium (p. 391)

orbital (or'buh-till) a volume of space in which a given electron occurs 90% of the time (p. 15)

order (or'dur) a category of classification between a class and a family (p. 290)

organelle  (or-guh-nel') a membrane-bound body in the cytoplasm of a cell; there are several kinds, each with a specific function (e.g., mitochondrion, chloroplast)l (p. 32)

organic ( or-gan'ik) pertaining to or derived from living organisms and pertaining to the chemistry of carbon-containing compounds (p. 21 )

osmosis   ( oz-moh' sis ) the diffusion of water or other solvents through a differentially permeable membrane from a region of higher concentration to a region of lower concentration (p. 156)

osmotic potential  (oz-mot'ik puh-ten'shil) potential pressure that can be developed by a solution separated from pure water by a differentially permeable membrane (the pressure required to prevent osmosis from taking place) (p. 157)

osmotic pressure  (oz-mot'ik presh'ur) see osmotic potential outcrossing ( out'kross-ing) crosspollination between

individuals of the same species (p. 258) ovary  (oh'vuh-ree) the enlarged basal portion of a pistil that

contains an ovule or ovules and usually develops into a fruit (p. 133)

ovule (oh'vyool) a structure of seed plants that contains a female gametophyte and has the potential to develop into a seed (p. 133, 422)

oxidation-reduction  reactions (ok-suhday'shun ree-duk'shun) chemical reactions involving gain or loss of electrons to or from a compound (p.172)

P palisade mesophyll   (pal-uh-sayd' mez'uhfil) mesophyll

having one or more relatively uniform rows of tightly packed, elongate, columnar parenchyma (chlorenchyma) cells beneath the upper epidermis of a leaf (p. 115)

palmately compound; palmately veined  (pahl'mayt-lee kom'pownd; pahl'maytlee vaynd) having leaflets or principal veins radiating out from a common point(p. 110, 112) I. Ribosomes, which are considered organelles are an exception in that they are not bounded b) a membrane.

papilla (pl. papillae) (puh-pil'uh; pl. puhpill'ay) a small, usually rounded or conical protuberance (p. 331 )

parenchyma  (puh-ren'kuh-muh) thin-walled cells varying in size. shape, and function; the most common type of plant cell (p. 55)

parental type  (pah-renn'tuhl typ) an offspring with the same combination of alleles as one of its parents (p. 249)

parthenocarpic  (par-thuh-noh-kar'pik) developing fruits from unfertilized ovaries; the resulting fruit is. therefore, usually seedless (p. 448)

particle gun (pahrt'ik-kuhl gunn) a machine capable of changing the genetic makeup of plant tissue by shooting DNA-coated particles into it (p. 260)

passage cell (pas'ij sel) a thin-walled cell of an endodermis (p. 70)

pectin  (pek'tin) a water-soluble organic compound occurring primarily in the middle lamella; when combined with organic acids and sugar, it becomes a jelly (p. 35)

pedicel  (ped'i-sel) the individual stalk of a flower that is part of an inflorescence (p.132)

peduncle  (pee'dun-kul) the stalk of a solitary. flower or the main stalk of an inflorescence (p. 132)

peptide bond (pep'tyd bond) the type of chemical bond formed when two amino acid~ link together ill the synthesis of proteins (p. 24 )

perennial  (puh-ren'ee-u]) a plant that continues to Jive indefinitely after flowering (p 132)

perianth  (pari'ee-anth) the calyx and corolla of a flower (p. 132)

pericarp  (per'uh-karp) collective term for all the layers of a fruit wall (p. 136)

pericycle  (per'uh-sy-kul) tissue sandwiched between the endodermis and phloem of a root; often only one or two cells wide in transverse section; the site of origin of lateral roots (p. 71)

periderm  (pair'uh-durm) outer bark; composed primarily of cork cells (p. 62)

perigynous (purr-idj'uh-nuss) having flower parts attached around the ovary; the flower parts are usually attached to a cup (p. 449)

peristome  (per'uh-stohm) one or two series of flattened, often ornamented structures (teeth) arranged around the

margin of the open end of a moss sporangium; the teeth are sensitive to changes in humidity and facilitate the release of spores (p. 39 J )

petal  (pet'ul) a unit of a corolla; it is usually both flattened and colored (p. 132)

petiole  (pet'ee-ohl) the staJk of a leaf (p.87,J10) Pfar-red, or Pfr (pee-far-red or pee-ef-ahr) a form of

phytochrome (which see) (p.215) pH (pee-aitch) a symbol of hydrogen ion concentration

indicating the degree of acidity or alkalinity (p. 82) phage (fayj) see bacteriophage phellogen (fel'uh-jun) see cork cambium phenotype   (fee'noh-typ) the physical appearance of an

organism (p. 242) pheromone  (fer'uh-mohn) something produced by an

organism that facilitates chemical communication with another organism (p. 544 )

phloem  (flohm) the food-conducting tissue of a vascular plant (p. 59)

photon (foh'ton) a unit.of light energy (p. 177) photoperiodism  (foh-toh-pir'ee-ud-izm) the initiation of

flowering and certain vegetative activities of plants in response to relative lepgths of day and night (p. 214)

photosynthesis  (foh-toh-sin'thuh-sis) the conversion of light energy to chemical energy; water, carbon dioxide, and chlorophyll are all essential to the process, which ultimately produces carbohydrate, with oxygen being released as aby-product(p.14,171)

photosynthetic unit (foh-toh-sin-thet'ik yew'nit) one of two groups of about 250 to 400 pigment molecules each that function together in chloroplasts in the light reactions of photosynthesis; the units are exceedingly numerous in each chloroplast (p. 176)

photosystem   (foh'toh-sis-tum) collective term for a specific functional aggregation of photosynthetic units (p. 178)

phragmoplast (frag'mo-plasO a complex of microtubules and endoplasmic reticulum that develops during telophase of mitosis (p. 50)

phytochrome  (fy'tuh-kl.ohm) protein pigment associated with the absorption of light; it is found in the cytoplasm of cells of green plants and occurs in interconvertible active and inactive forms (PCarred and p red); it facilitates a plant's capacity to detect the presence (or absence) and duration of light (p. 215)

pilus (pl. pili) (py'lis; pl. py'lee) the equivalent of a conNgation tube in bacteria (p. 302)

pinna  (pl. pinnae) (pin'uh; pl. pin'ee) a primary subdivision of a fern frond; the term is also applied to a leaflet of a compound leaf(p. 410)

pinnately compound ; pinnately veined (pin'ayt-lee kom'pownd; pin'ayt-lee vaynd) having leaflets or veins on both sides of a common axis (e.g., rachis, midrib) to which they are attached (p. 110, 112)

pistil  (pis'tulJ a female reproductive structure of a flower, composed of one or more carpels and consisting of an ovary, style, and stigma(p. 133)

pit  (pit) a more or less round or elliptical thin area in a cell wall; pits occur in pairs opposite each other, with or ~ithout shallow, domelike borders (p.59)

pith  (pith) central tissue of a dicot stem and certain roots; it usually consists of parenchyma cells that become proportionately less of the volume of woody plants as cambial activity increases the organ's girth (p. 88)

plankton  (plank'ton) free-floating aquatic organisms that are mostly microscopic (p. 327)

plant anatomy (plant uh-nat'uh-mee) the botanical discipline that pertains to the internal structure of plants (p. 8)

plant community (plant kuh-rnyu'nuh-tee) an association (plants inhabiting a common environment and interacting with one another (p. 490)

plant ecology (plant ee-koll'uh-jee) the science that deals with the relationships and interactions between plants and their environment (p. 9)

plant geography (plant jee-og'ruh-fee) the botanical discipline that pertains to the broader aspects of the space relations of plants and their distribution over the surface of the earth (p. 9)

plant morphology (plant mor-fol'uh-jee) the botanical discipline that pertains to plant form and development (p. 9)

plant physiology (plant fiz-ee-ol'uh-jee) the botanical discipline that pertains to the metabolic activities and processes of plants (p. 8)

plant taxonomy (plant tak-son'uh-mee) the botanical discipline that pertains to the classification, naming, and identification of plants (p. 9 )

plasma membrane (plaz'muh mem'brayn) the outer boundary of the protoplasm of a cell; also called cell membrane, particularly in animal cells (p. 36)

plasmid  (plaz'mid) one of up to 30 or40 small, circular DNA molecules usually present in a bacterial cell (p. 260)

plasmodesma (pl. plasmodesmata) (plazmuh-dez'muh; pi. plaz-muh-dez'muhtah) minute strands of cytoplasm that extend between adjacent cells through pores in the walls (p. 35)

plasmodium  (pl. plasmodia) (plaz-moh' dee-um; pl. plaz-moh'dee-ah) the multinucleate, semiviscous liquid. active form of slime mold; it moves in a ..crawling-flowing" motion (p. 348)

plasmolysis  (plaz-mol'uh-sis) the shrinking in volume of the protoplasm of a cell and the separation of the protoplasm from the cell wall due to loss of water via osmosis (p. 157)

plastid (plas'tid) an organelle associated primarily with the storage or manufacture of carbohydrates (e.g., leucoplast, chloroplast) (p. 40)

plumule (ploo'myooO the terminal bud of the embryo of a seed plant (p. 147)

pneumatophore (noo-mat'oh-for) spongy root extending above the surface of the water, produced by a plant growing in water; pneumatophores facilitate oxygen absorption (p. 73)

pole (pohl) an invisible focal point toward each end of a cell from which spindle fibers extend in arcs during mitosis or meiosis (p. 224)

pollen grain  (pahl'un grayn) a structure derived from the microspore of seed plants that develops into a male gametophyte (p. 133,425, 444)

pollen tube  (pahl'un t(y)oob) a tube that develops from a pollen grain and conveys the sperms to the female gametophyte (p. 426, 447)

pollination  (pahl-uh-nay'shun) the transfer of pollen from an anther to a stigma (p.447)

pollinium (pi. pollinia) (pah-lin'ee-um; pl. pah-lin'ee-ah) a cohesive mass of pollen grains commonly found in members of the Orchid Family (Orchidaceae) and the Milkweed Family (Asclepiadaceae) (p.453)

polymer  (pahl'i-mur) a large molecule composed of many monomers (p. 21 )

polymerase  (poh-limm'err-ace) an enzyme that creates a polymer (e.g., DNA polymerase synthesizes DNA) (p.234)

polypeptide  (pahl-ee-pep'tide) a chain of amino acids (p. 23)

polyploidy  (pahl'i-ploy-dee) having more than two complete sets of chromosomes per cell (p. 282)

pome  (pohm) a simple fleshy fruit whose flesh is derived primarily from the receptacle (p. 138)

population (pop-yew-lay'shun) a group of organisms, usually of the same species, occupying a given area at the same time (p.490)

pred or pr (pee-red or pee-ahr) a form of phytochrome (which see) (p. 215)

pressure-flow hypothesis  (presh'ur floh hy-poth'uh-sis) the theory that food substances in solution in plants flow along concentration gradients between the sources of the food and sinks (places where the food is utilized) (p. 165)

prickle  (prik'uhl) a pointed outgrowth from an epidermis or cortex beneath the epidermis (p. 119)

primary consumer (pry'mer-ree konsoo'mur) organism that feeds directly on producers (p. 492)

primary tissue (pry'mer-ee tish'yu) a tissue produced by an apical meristem (e.g., epidermis, cortex, primary xylem and phloem, pith) (p. 54)

primordium  (pry-mord'ee-um) an organ or structure (e.g., leaf, bud) at its earliest stage of development (p. 88)

procambium  (proh-kam'bee-um) a tissue produced by the primary meristem that differentiates into primary xylem and phloem (p. 54, 68, 88)

producer (pruh-dew'sur) an organism that manufactures food through the process of photosynthesis (p. 492)

prokaryotic  (proh-kair-ee-ot'ik) having a cell or cells that lack a distinct nucleus and other membrane-bound organelles (e.g., bacteria) (p. 32)

promoter region (proh-moh'turr ree'jin) the DNA sequence to which RNA polymerase binds to initiate transcription (p. 237)

proplastid (proh-plas'tid) a tiny, undifferentiated organelle that can duplicate itself and that may develop into a chloroplast, leucoplast, or other type of plastid (p. 42)

protein (proh'tee-in or proh'teen) a polymer composed of many amino acids linked together by peptide bonds (p. 23)

protein sequencer (proh'tee-in or proh' teen see'kwens-urr) a machine that reveals the sequence of-amino acids in a protein (p. 260)

prothallus  (pl. prothalli) (proh-thal'us; pl. proh-thal' eye) the gametophyte of ferns and their relatives; also called prothallium (p. 412, 4l3)

protoderm (proh'tuh-durm) the primary meristem that gives rise to the epidermis (p. 54, 68, 88)

proton (proh'ton) a positively charged particle in the nucleus of an atom (p. 15)

protonema  (proh-tuh-nee'muh) a green, usually branched, threadlike or sometimes platelike growth from a bryophyte spore; it gives rise to "leafy" gametophytes (p. 388)

protoplast  (proh'toh-plast) the unit of protoplasm ~.ithin a plant cell wall (p. 259)

protoplast fusion (proh'toh-plast few'szhinn) the process of combining in vitro two protoplasts in one cell (p. 259)

pruning  (proon'ing) removal of portions of plants for aesthetic purposes, for improving quality and size of fruits or flowers, or for elimination of diseased tissues(p.594)

pyrenoid (py'ruh-noyd) a small body found on the chloroplasts of certain green algae and homworts; pyrenoids are associated with starch accumulation; they may occur singly on a chloroplast, or they may be numerous (p. 328)

pyruvic acid  (py-roo'vik as'id) the organic compound that is the end product of the glycolysis phase of respiration (p. 186)

Q quantitative trait (kwan'tuh-tay-tiv trait) a trait controlled

by several genes and influenced by the environment; it is usually measured on a continuous scale (p. 248)

quiescence  (kwy'ess-ens) a state in which a seed or other plant part will not germinate or grow unless environmental conditions normally required for growth are present (p. 217)

R rachis (ray'kiss) the axis of a pinnately compound leaf or

frond extending between the lowermost leaflets or pinnae and the terminal leaflet or pinna ( corresponds with the midrib of a simple leat) (p. 110)

radicle  (rad'i-kuhl) the part of an embryo in a seed that develops into a root (p.66. 148)

ray  (ray) radially oriented tiers of parenchyma cells that conduct food. water. and other materials laterally in the stems and roots of woody plants; they are generally continuous across the vascular cambium between the xylem and the phloem: the portion within the wood is called a xylem ray, while the extension of the same ray in the phloem is called a phloem ray (p. 59)

receptacle  (ree-sep'tuh-kuhl) the commonly expanded tip of a peduncle or pedicel to which the various parts of a flower (e.g., calyx, corolla) are attached (p. 132)

recessive  (ree-ses'iv) a condition in which the phenotypic expression of one allele of a gene is masked by the phenotypic expression of another (dominant) allele (p. 242)

recombinant DNA  (ree-komm'bin-int dee-en-ay) a molecule created in vitro containing DNA trom at least two organisms (p. 259)

recombinant type  (ree-komm'bin-int typ) an individual offspring that due to recombination has a combination of alleles different from either of its parents (p. 249)

red tide (red tyd) the marine phenomenon that results in the water becoming temporarily tinged with red due to the sudden proliferation of certain dinoflagellates that produce substances poisonous to animal life and humans (p. 342)

reproduction (ree-proh-duk'shun) the development of new individual organisms through either sexual or asexual means (p. 13)

resin canal (rez'in kuh-na1') a tubular duct of many conifers and some angiosperms that is lined with resin-secreting cells (p. 422)

respiration  (res-puh-ray'shun) the cellular breakdown of sugar and other foods, accompanied by release of energy; in aerobic respiration, oxygen is utilized (p. 14,171,186,189)

restriction enzyme  (ruh-strikt'shunn en'zym) an enzyme capable of severing a DNA molecule at a specific site (p. 260)

rhizoid  (ry'zoyd) a delicate root- or roothair-like structure of algae, fungi, the gametophytes of bryophytes, and certain structures of a few vascular plants; functions in anchorage and absorption but have no xylem of phloem (p. 357)

rhizome  (ry'zohm) an underground stem, usually horizontally oriented, that may be superficially rootlike in appearance but that has definite nodes and internodes (p. 100)

ribosome (ry'boh-sohm) a granular particle composed of two subunits consisting of RNA and proteins; ribosomes lack membranes, are the sites of protein synthesis, and are very numerous in living cells (p. 40, 237)

RNA (ar-en~ay) the standard abbreviation for ribonucleic acid, an important cellular molecule that occurs in three forms, all involved in communication between the nucleus and the cytoplasm and in the synthesis of proteins (p. 26)

root  (root) a plant organ that functions in anchorage and absorption; most roots are produced below ground (p. 54)

root cap  (root kap) a thimble-shaped mass of cells at the tip of a growing root; functions primarily in protection (p. 67)

root hair  (root hair) a delicate protuberance that is part of an epidermal cell of a root; root hairs occur in a zone behind the growing tip (p. 68)

root nodule  (root nodd'yewl) a small swelling associated with nitrogen-fixing bacteria that invade the roots of leguminous plants and alders (p. 78)

runner  (run'ur) a stem that grows horizontally along the surface of the ground; typically has long internodes; see also stolon (p. 100)

S salt (salt) a substance produced by the bonding of ions that

remain after hydrogen and hydroxyl ions of an acid and a base combine to form water (p. 19)

samara  (sah-mair'uh) a dry fruit whose pericarp extends around the seed in the form of a wing (p. 142)

saprobe (sap'rohb) an organism that obtains its food directly from nonliving organic matter (p. 304)

sapwood  (sap'wood) outer layers of wood that transport water and minerals in a tree trunk; sapwood is usually lighter in color than heartwood (p. 94 )

schizocarp  (skit'soh-karp) a twin fruit unique to the Parsley Family (Apiaceae) (p. 142)

science (sy'ints) a branch of study involved with the systematic observation, recording, organization, and classification of facts from which natural laws are derived and used predictiveJy (p. 7)

scion (sy'un) a seglpent of plant that is grafted onto a stock (p. 268)

sclereid  (sklair'id) a sclerenchyma cell that usually has one axis not conspicuously longer than the other; it may vary in shape and is heavily lignified (p. 55)

sclerenchyma  (skJuh-ren'kuh-muh) tissue composed of lignified cells with thick walls; the tissue functions primarily in strengthening and support (p. 55)

secondary consumer (sek'on-dair-ee konsoo'mer) an organism that feeds on other consumers (p. 492)

secondary tissue (sek'un-der-ee tish'yu) a tissue produced by the vascular cambium or the cork cambium (e.g., virtually all the xylem and phloem in a tree trunk) (p. 68)

secretory cell, tissue (see'kruh-tor-ee sel, tish'yu) cell or tissue producing a substance or substances that are moved outside the cells (p. 63)

seed (seed) a mature ovule containing an embryo and bound by a protective seed coat (p. 133,222)

seed coat   (seed' koht) the outer boundary layer of a seed; it is developed from the integument(s) (p. 422,426,443)

semiconservative replication (semm'eekDn-surv-uh-tiv repp-lee-kay'shun) DNA replication mechanism that ensures each daughter molecule has one parental strand and one new strand (p. 234 )

semipermeable membrane  (sem-ee-pur'me-uh-bil mem-brayn) see differentially permeable membrane

senescence (suh-ness'ints) the breakdown of cell components and membranes that leads to the death of the cell (p. 205)

sepal  (see'puhl) a unit of the calyx that frequently resembles a reduced leaf; sepals often function in protecting the unopened flower bud (p. 132)

sessile  (sess'uhl) without petiole or pedicel; attached directly by the base {p. 110)

seta (see'tuh) the stalk of a bryophyte sporophyte (p. 386) sexual reproduction (seksh'yule ree-prohduk'shun)

reproduction involving the union of gametes (p. 222) short-day plant (short-day plant) a plant in which flowering

is initiated when the days are shorter than its critical photoperiod (p, 214)

sieve plate  (siv playt) an area of the wall of a sieve tube member that contains several to many perforations that permit cytoplasmic connec1ions between similar adjacent cells, the cytoplasmic strands being larger than pla.5modesmata (p. 60)

sieve tube  (siv t(y)oob) a column of sievetube members arranged end to end; food is conducted from cell to cell through sieve plates (p. 60)

sieve tube member (siv t(y)oob mem'bur) a single cell of II sieve tube (p. 60)

silique   (suh-leek') a dry fruit that splits along two "seams," with the seeds borne on a central partition (p. 138)

simple fruit  (sim'pul froot) a fruit that develops from a single pistil (p. 136)

simple leaf  (sim'pulleef) a leaf with the blade undivided into leaflets (p. 110)

slime mold (slym mold) a simple organism that moves like an amoeba but resembles a fungus when reproducing (p. 348)

solvent (sol'vent) a substance (usually liquid) capable of dissolving another substance (p. 156)

somatic hybrid  (soh-matt'ik hy'brid) a plant produced by protoplast fusion (p.259)

somatic mutation  (soh-matt'ik mewtay'shun) a mutation in a somatic (body) cell; such a mutation is not passed on to offspring (p. 238)

sorus  (pl. sori) (sor'uss; pl. sor'eye) a cluster of sporangia; the term is most frequently applied to clusters of fern sporangia (p. 411)

speciation  (spee-see-ay'shun) the origin of new species through evolution (p. 239)

species  (spee'seez; species is spelled and pronounced the same way in either singular or plural form; there is no such thing as a specie) the basic unit of classification; a population of individuals capable of interbreeding freely with one another but because of geographic, reproductive, or other barriers, do not in nature interbreed with members of other species (p. 288)

sperm (spurm) a male gamete; except for those of red algae and angiosperms. sperms are frequently motile and are usually smaller than the corresponding female gametes (p. 222, 332, 426)

spice (spyss) an aromatic organic plant product used to season or flavor food or drink (p. 571 )

spindle (spin'duhl) an aggregation offiberlike threads (microtubules) that appears in cells during mitosis and meiosis; some threads are attached to the centromeres of chromosomes, whereas other threads extend directly or in arcs between two invisible points designated as poles (p. 48, 49)

spine (spyn) a relatively strong, sharppointed. woody structure usually

located on a stem; it is usually a modifled leaf or stipule (p. 119)

spongy mesophyll  (spun'jee mez'uh-fil) mesophyll having loosely arranged

cells and numerous air spaces; it is generally confined to the lower part of the interior of a leaf just above the lower epidermis (p. 115)

sporangiophore  (spuh-ran'jee-uh-for) the stalk on which a sporangium is produced (p.'358)

sporangium  (pl. sporangia) (spuh-ran'jeeurn; pl. spuh-ran'jee-uh) a structure in which spores are produced; it may be either unicellular or multicellular (p. 349, 358, 382)

spore  (spor) a reproductive cell or aggregation of cells capable of developing directly into a gametophyte or other

body without uniting with another cell (Note: a bacterial spore is not a reproductive cell but is an inactive phase that enables the cell to survive under adverse conditions); sexual spores formed as a result of meiosis are often called meiospores; spores produced by mitosis may be referred to as vegetative spores(p. 227, 349, 358)

sporocyte  (spor'oh-site) a diploid cell that becomes four haploid spores or nuclei as a result of undergoing meiosis (p. 227, 387)

sporophyll  (spor'uh-fil) a modified leaf that bears a sporangium or sporangia (p. 400)

sporophyte  (spor'uh-fyt) the diploid (2n) spore-producing phase of the life cycle of an organism exhibiting Alternation of Generations (p. 227)

stamen  (stay'min) a pollen-producing structure of a flower; it consists of an anther and usually also a filament (p. 133)

stele  (steel) the central cylinder of tissues in a stem or root; usually consists primarily of xylem and phloem (p. 90)

stem  (stem) a plant axis with leaves or enalions (p. 54) stigma (stig'muh) the pollen receptive area ofapistil(p.133) stipe  (styp) the supporting stalk of seaweeds, mushrooms,

and certain other stationary organisms (p. 337) stipule  (stip'yool) one of a pair of appendages of varying

size, shape, and texture present at the base of the leaves of some plants (p. 87)

stock  (stok) the rooted portion of a plant to which a scion is grafted (p. 268)

stolon  (stoh'lun) a stem that grows vertically below the surface of the ground; it typically has relatively long internodes; see also runner (p. 100)

stoma  (pl. stomata) (stoh'muh; pl. stoh'mah-tuh) a minute pore or opening in the epidermis of leaves, herbaceous stems, and the sporophytes of horn worts (Anthoceros); it is flanked by two guard cells that regulate its opening and closing and thus regulate gas exchange and transpiration (p. 61, 113)

strobilus  (pl. strobili) (stroh'buh-luss; pl. stroh'buh-leye) an aggregation of sporophylls on a common axis; it usually resembles a cone or is somewhat conelike in appearance (p. 400, 407)

stroma  (stroh'muh) a region constituting the bulk of the volume of a chloroplast or other plastid; it contains enzymes that in chloroplasts playa key role in carbon fixation, carbohydrate synthesis, and other photosynthetic reactions (p.40)

style  (styl) the structure that connects a stigma and an ovary (p. 133)

subculture (subb'kull-choor) the Iransfer of tissue culture plantlets or plant parts to a new medium, usual1y as a form of propagation (p. 270)

suberin {soo'buh-rin) a fatty substance found primarily in the cel1 wal1s of cork and the Casparian strips of endodermal cel1s (p. 62, 90)

succession (suk-sesh'un) an orderly progression of changes in the composition of a community from the initial development of vegetation to the establishment of a climax community (p. 498)

sucrose (soo'krohs) a disaccharide composed of glucose and fructose; the primary form in which sugar produced by photosynthesis is transported throughout a plant (p. 21)

superior ovary (soo-peer'ee-or oh'vuh ree) an ovary that is free from the calyx, corolla, and other floral parts, so the sepals and petals appear to be attached at its base (p. 133,449)

symbiosis  (sim-by-oh'siss) an intimate association between two dissimilar organisms that benefits both of them (mutualism) or is harmful to one of them (parasitism) (p. 300)

syngamy  (sin'gam-mee) a union of gametes; fertilization (p. 228)

T 2n (too-en) having two sets of chromosomes; diploid (p.

227) 3n (three-en) having three sets of chromosomes; triploid (p.

227,447) tendril  (ten'dril) a slender structure that coils on contact

with a support of suitable diameter; it usually is a modified leaf or leaflet and aids the plant in climbing (p. 103, 118)

thallus   (pl. thalli) (thal'uss; pl. thai' eye) a multicellular plant body that is usually flattened and not organized into roots, stems, or leaves (p. 337 , 375, 385)

thorn (thorn) a pointed specialized stem (p. 119)

thylakoid  (thy'luh-koyd) coin-shaped membranes whose contents include chlorophyll; they are arranged in stacks that form the grana of chloroplasts {p. 41 )

tip layering (tipp lay'urr-ing) asexual propagation involving the burying of the tip of a flexible stem in soil to induce the formation of adventitious roots; the rooted portion is then cut from the parent plant and grown separately (p. 267)

tissue (tish'yu) an aggregation of cells having a common function (p. 54)

tissue culture (tish'yu kul'chur) the culture of isolated living tissue on an artificial medium (p. 269)

totipotency (toh-tuh-poh'ten-see) the potential of a cell to develop into a complete plant (p. 269)

tracheid  (tray'kee-id) a xylem cell that is tapered at the ends and has thick walls containing pits (p. 59)

transcript (tran'skriptt) the RNA molecule formed by transcription (p. 237)

transcription  (trans-krip'shun) the copying of a sequence of DNA nucleotides into an RNA sequence (p. 236)

transformation  (trans-forr-may'shun) the transfer of DNA from one organism to another(p.260)

transgenic plant  (trans-jeen'ik plant) a plant containing recombinant DNA (p. 259)

translation  (trans-lay'shun) the process of decoding RNA into protein (p. 237)

translocation  (trans-loh-kay'shun) a chromosomal rearrangement resulting from a segment of one chromosome being moved to another chromosome (p. 240)

transpiration   (trans-puh-ray'shun) loss of water in vapor form; most transpiration takes place through the stomata (p. 110, 266)

transposable genetic element  (transPOh'suh-biljuh-nett'ik e!'uh-mint) a DNA sequence transpasan) capable of being moved from one chromosomal location to another (p. 231 )

transposition  (trans-poh-zish'unn) the movement of a transposable genetic element (p. 231)

tropism  (troh'pizm) response of a plant organ or part to an external stimulus, usually in the direction of the stimulus (p. 207)

tuber  (t(y)oo'bur) a swollen, fleshy underground stem (e.g., white potato) (p. 100)

turgid  (tur'jid) firm or swollen because of internal water pressures resulting from osmosis (p. 157)

turgor movement   (turr'gor moov'mint) the movement that results from changes in internal water

pressures in a plant part (p. 210) turgor pressure  (tur'gur presh'ur) pressure within a cel]

resulting from the uptake of water (p. 157)U

unisexual (yu-nih-seksh'yu-ul) a term usually applied to a flower lacking either stamens or a pistil (p. 450)

V vacuolar membrane  (vak-yu-oh'\ur mem'brayn) the

delimiting membrane of a cell vacuole; also called tonoplast (p.43)

vacuole   (vak'yu-ohl) a pocket of fluid that is separated from the cytoplasm of a cell by a membrane; it may occupy more than 99% of a cell's volume in plants; also, food-storage or contractile pockets within the cytoplasm of unicellular organisms (p. 43)

vascular bundle  (vas'kyu-lur bun'dul) a strand of tissue composed mostly of xylem and phloem and usually enveloped by a bundle sheath (p. 91 )

vascular cambium  (vas'kyu-lur kam'beeurn) a narrow cylindrical sheath of cells that produces secondary xylem and phloem in sterns and roots (p. 54, 90, 268)

vascular plant  (vas'kyu-lur plant) a plant having xylem and phloem (p. 382)

vein  (vayn) a term applied to any of the vascular bundles that form a branching network within leaves (p. 115)

velamen root (vel'uh-min root) an aerial root with a multilayered epidermis believed to function in retarding moisture loss (p. 60)

venter  (ven'tur) the site of the egg in the enlarged basal portion of an archegonium (p. 389)

vessel  (ves'uhl) one of usually very numerous cylindrical "tubes" whose cells have lost their cytoplasm; occur in the xylem of most angiosperms and a few other vascular plants; each vessel is composed of vessel members laid end to end; the perforated or open-ended walls of the vessel members permit water to pass through freely (p. 59)

vessel element  (ves'uhl el'uh-ment) a single cell of a vessel (p. 59)

viability  (vy-uh-bill'it-ee) capacity of a seed or spore to germinate (p. 265)

virus  (vy'riss) a minute particle consisting of a core of nucleic acid, usually surrounded by a protein coat; it is incapable of growth alone and can reproduce only within, and at the expense of, a living cell (p. 317, 318)

vitamin (vyt'uh-min) a complex organic compound produced primarily by photosynthetic organisms; various vitamins are essential in minute amounts to facilitate enzyme reactions in living cells (p.198)

W water-splitting (photolysis)  (waw'tuhr split-ing foh-tohl'uh-

siss) a process in photosystem II of photosynthesis whereby water molecules are split with the release of oxygen (p.180)

whorled  (wirld) having three or more leaves or other structures at a node (p. 110)

X xerosere (zer'roh-sear) a primary succession that initiates

with bare rock (p.498) xylem  (zy'lim) the tissue through which most of the water

and dissolved minerals utilized by a plant are conducted; it consists of several types of cells (p.59)

Z zoospore  (zoh'uh-spor) a motile spore occurring in algae

and fungi (p.329) zygote  (zy' goht) the product of the union of two gametes

(p.222, 226, 447)AABDOMEN - The third or posterior major division of the insect body; consists normally of nine or ten apparent segments; bears no functional legs in the adult stage, but may bear prolegs or false legs in the larval stage.[1] Fin. Swe.ABIOTIC PATHOGEN - A nonliving, disease-causing entity, e.g., drought, salt, air pollutants.[1]Fin. Swe.ACUTE INJURY - Injury, usually involving necrosis, which develops within several hours to a few days after a high dose exposure to a pollutant; expressed as fleck, scorch, bifacial necrosis, etc.[1] Fin. Swe.AECIAL STAGE (aecium) - A spore stage of the rust fungi; a cuplike structure bearing aeciospores.[1] Fin. Swe.ALTERNATE HOST - One of two taxonomically different hosts required by a heteroecious rust fungus to complete its cycle; also applies to some insects.[1] Fin. Swe.ANTERIOR - In front; before; opposite of posterior.[1] Fin. Swe.ANTHOCYANOSIS - Presence of abnormal red-purple coloration in foliage.[1]ASEXUAL STAGE - Vegetative; without sexual organs or spores.[1] Fin. Swe.AUTOECIOUS - Completing entire life cycle on one host; especially applied to the rust fungi.[1]Fin. Swe.

BBANDING - A foliar symptom characterized by a limited zone of necrotic or discolored tissue traversing the leaf, e.g., the band of tissue on a pine needle injured by SO2 or 03.[1]BASIDIAL STAGE (basidium)- A spore stage of the rust fungi; a specialized structure in the Basidiomycetes bearing basidiospores.[1] Fin. Swe.BASIDIOCARPS - Sexual fruiting structure in the Basidiomycetes; conks, sporophore, mushrooms, etc.[1] Fin. Swe.BIFACIAL NECROSIS - Death of plant tissues, extending from the upper to the lower leaf surface.[1]BIOINDICATOR SPECIES - Species, varieties, or cultivars sufficiently sensitive to a specific pollutant to be useful as indicators for the presence of that pollutant.[1] Fin. Swe.BIOTIC PATHOGEN - A living organism capable of inciting disease, e.g., fungi, bacteria, viruses, etc.[1] Fin. Swe.BLEACHING - Loss of normal color, tending toward white, cream, or tan coloration.[1] Fin. Swe. BLIGHT - A common term for several different diseases; usually applied to those where leaf damage is sudden and severe.[1] Fin. Swe.BRONZING - A golden brown discoloration that usually appears on the lower surface of leaves and is often an advanced stage of the silvering or glazing typical of injury by PAN and other oxidants; brown coloration on needles due to spider mite infestation.[1] Fin. Swe.

CCALLUS TISSUE - A protective tissue of thin-walled cells developed on wound surfaces, often beginning at the edges of a wound.[1] Fin. Swe.CANKER - A plant disease symptom characterized by a sharply defined necrosis of cortical tissue, often sunken below bark surface.[1] Fin. Swe.CHEWING INSECTS - Insects that consume all tissues of leaves or portions of leaves, using robust mandibles for chewing.[1] Fin.CHLOROSIS - Yellowing of plant tissue due to failure of chlorophyll synthesis or to chlorophyll destruction.[1] Fin. Swe.CHLOROTIC DWARF - An abiotic disease of Pinus strobus characterized by reduced growth, chlorosis and mottling of the needles, and premature abscission of all but current needles.[1]CHRONIC INJURY - Injury which develops after long-term or repeated low dose exposure to an air pollutant expressed as chlorosis, bronzing, premature senescence, reduced growth, etc.[1]Fin. Swe.CLONAL LINES - A group of plants originating from buds or cuttings from the same individual.[1]CONK - The fruiting structure of a wood-rotting fungus, especially of one of the Polyporaceae.[1]Fin. Swe.COCOON - A covering, composed partly or wholly of silk or other sticky fiber, spun or constructed by many larvae as a protection for the pupal stage.[1] Fin. Swe.CORNICLES - The posterior dorsal erect or semi-erect tubules of aphids which secrete a waxy defensive liquid to protect the insect against enemies; short, blunt horns or rounded projections occurring on the abdomen.[1]CRAWLER - The first instar motile nymphal stage of scale insects and mealybugs, which moves to a new feeding site before settling down to a sessile existence for the rest of its developmental life.[1]CRINKLING - Bending or twisting of foliage without breaking; wrinkling.[1] Fin. Swe.CRYPTIC - Hidden or concealed.[1] Fin. Swe.

DDEFOLIATOR - Any chewing insect that consumes the leaves or needles of plants.[1] Fin. Swe. DELIQUESCENT - To ramify into fine divisions, such as abnormal numbers of buds, twigs, branches, or leaves, e.g., witches' broom development.[1] Fin. Swe.DORSAL - Of or belonging to the upper surface; top.[1] Fin. Swe.DORSOVENTRAL - From top to bottom; from the upper surface to the lower surface.[1]DORSUM - The upper surface; top.[1] Fin. Swe.DOSE - A measured concentration of a toxicant for a known duration of time (concentration per unit time).[1]

EEGG GALLERY - A long, narrow tunnel along the sides of which eggs are deposited in small niches; the pattern of construction is often diagnostic of a particular species of insect.[1] Fin. Swe. EGG MASS - Cluster of eggs, usually in a matrix of body hairs or wing scales from the female adult and/or a mucilaginous cementing secretion.[1]ELYTRA - The anterior leathery or chitinous wings of beetles and leafhoppers; serve as coverings to the hind wings and commonly meet at rest in a straight line down the middle of the dorsum.[1] Fin. Swe.ENGRAVER - Beetle which feeds in the phloem-cambium region of woody plants, often scoring or engraving adjacent sapwood tissues.[1]EPICORMIC BRANCHING - Branches arising from buds in bark along mainstem, most commonly occurring in trees under crown stress; also called watersprouts.[1] Fin. Swe.EPIDEMIC - A change, usually a sudden increase, in a disease within a population.[1] Fin. Swe.

FFOREWINGS - Front pair of wings.[1] Fin. Swe.FLECK - White to tan necrotic lesions up to a few millimeters in length or diameter, usually confined to the upper surface of leaves.[1] Fin. Swe.FRASS - Solid larval insect excrement; mixed with wood fragments in woodboring or bark-boring insects.[1] Fin. Swe.FRUITING BODY - A specialized structure, often macroscopic, on or in which spores are produced.[1] Fin. Swe.FUMIGATION - The natural or controlled exposure of plants to toxic gases or volatile substances.[1] Fin. Swe.

GGALL" - A swelling or outgrowth of tissue induced by a pathogen or insect on a slant.[1] Fin. Swe.

GENERATION - The successive developmental stages from reproduction to reproduction, e.g., egg, larva, pupa, adult.[1] Fin. Swe.GIRDLING - Destruction of tissue in a ring around a twig, branch, or stem.[1] Fin. Swe.GOUT - Formation of swellings at nodes or at the base of buds.[1]GREGARIOUS - Living in groups or communities.[1] Fin. Swe.GRUB - An insect larva; a term loosely applied, usually to larvae of Coleoptera; larva is thick-bodied with well-developed thoracic legs but no abdominal prolegs.[1] Fin. Swe.

HHETEROECIOUS - Requiring two taxonomically different hosts to be able to complete the entire life cycle, as in the rust fungi.[1] Fin. Swe.HONEYDEW - A sweetish excretion produced through the anus by certain insects, notably aphids and scale insects.[1] Fin. Swe.HOST - A living organism serving as a food source for a parasite.[1] Fin. Swe.HYSTEROTHECIUM - A sexual fruiting structure of the Ascomycete fungi, usually football-shaped or elongate in appearance and occurring on infected needles.[1] Fin. Swe.

IINSTAR - The insect itself during the time between molts in the larva or nymph, numbered to designate the various periods; i.e., the first instar is the insect between the egg and first molt.[1]INTERVEINAL - Between veins.[1] Fin. Swe.INTRAVEINAL - Associated along or within veins.[1] Fin. Swe.

LLARVA(plural = larvae) - The immature instars, between the egg and pupal stages, in an insect having a complete metamorphosis (egg, larva, pupa, adult). Larvae feed and grow but cannot fly, nor can they reproduce.[1] Fin. Swe.LESION - A wound; a well-marked, but limited, diseased area; a break or rupture through a tissue, especially a surface tissue.[1] Fin. Swe.LOOPER - A caterpillar in which some or all of the middle abdominal prolegs are wanting and which moves by placing the posterior part of the abdomen next to the thorax, forming a loop of the intervening segments, then extending the anterior part of the body forward.[1] Fin. Swe.

MMIDDORSAL - In the middle of the upper side or dorsum.[1]MIMICKING SYMPTOMS - Symptoms similar to those caused by pollutants but induced by other abiotic or biotic causal agents.[1]MINER - The larval stage of an insect which makes galleries or burrows between the upper and lower surfaces of leaf tissue.[1] Fin. Swe.MITE(S) - Small, often minute, arthropods in the order Acarina of the class Arachnida, which includes spiders, scorpions, and related forms. Mites have four pairs of legs vs. three pairs in insects.[1] Fin. Swe.MOLT - To cast off the outgrown skin or cuticle in the process of insect development; changing from one instar to the next.[1] Fin. Swe.MOTTLE - Irregular, diffuse patterns of chlorotic areas interspersed with normal green leaf tissue.[1] Fin. Swe.MOSAIC - A diseased condition where different portions of a leaf vary in amounts of chlorophyll, thus giving the leaf a mottled appearance; usually caused by viruses.[1] Fin. Swe.MYCELIUM - A mass or aggregate of hyphae; vegetative stage of fungi.[1] Fin. Swe.

NNAKED - Larva devoid of body hairs or setae; pupa not enclosed in a cocoon or other covering.[1]NECROSIS - Death.[1] Fin. Swe.NYMPH - The immature stage of insects, following hatching, which does not have a pupal stage, i.e., incomplete metamorphosis (egg, nymph, adult). Late instar nymphs may have nonfunctional rudimentary wings and/or genitalia.[1] Fin. Swe.

OOVIPOSITION - The act of depositing the eggs.[1] Fin. Swe.OVIPOSITOR - The egg-laying apparatus; the extended genitalia of a female insect.[1] Fin. Swe.

PPARASITE - An organism which lives on or in another living organism and obtains part or all of its nutrients from that other living organism.[1] Fin. Swe.PATHOGEN - Any agent of the environment capable of inciting disease.[1] Fin. Swe.PERITHECIUM" - A sexual fruiting structure of the Ascomycetes with an opening called the ostiole at or near its top.[1] Fin. Swe.POSTERIOR - Hind or hindmost; opposite of anterior.[1] Fin. Swe.PREDISPOSITION - The weakening of an organism by some factor(s) of either the physical or biotic environment so as to render the organism more susceptible to a pathogen.[1] Fin. Swe.PROLEG - Any process or appendage that serves the purpose of a leg; specifically, the fleshy, unjointed, ventral abdominal projections of caterpillars and certain sawfly larvae.[1] Fin. Swe.PUPA - The resting, inactive, nonfeeding instar in all holometabolous insects; the stage intermediate between the larva and the adult.[1] Fin. Swe.PYCNIAL STAGE (pycnium) - A flaskshaped spore stage of the rust fungi; oozes out spores in a sticky matrix.[1]PYCNIDIUM - An open-pored, flaskshaped fruiting structure in which asexual spores called conidia are produced.[1] Fin. Swe.

RRASPING - A type of feeding by insects which rub or grate the leaf surfaces with their mouthparts to obtain particles for consumption.[1] Fin. Swe. 

RESINOSIS - Resin flow through bark or from wounds or cankers on conifers.[1] Fin. Swe.RHIZOMORPH - A thread- or cordlike fungal structure made up of hyphae.[1] Fin. Swe.RINGSHAKE - Peripheral cracks in woody tissues of stems. The pattern of damage is concentric with the annual rings.[1] Fin. Swe.RINGSPOT - A circular area of chlorosis with a green center.[1]

SSAPROPHYTE - An organism living on dead organic matter.[1] Fin. Swe.SCORCH - Appearing as if tissues were burned by heat; usually affecting marginal portions of leaves.[1] Fin. Swe.SENESCENCE - Aging of tissues; growing old.[1] Fin. Swe.SESSILE - Attached or fastened; incapable of moving from place to place.[1] Fin.SETA (plural = setae) - Slender, hairlike or bristly projections arising from the epidermal layer on any part of the body of an insect.[1] Fin. Swe.SEXUAL STAGE - Reproductive stage of the life cycle of an organism.[1] Fin. Swe.SHOTHOLES - Small holes in a leaf caused by feeding activity and giving the appearance of injury via a shotgun.[1]SIGN - The actual presence of the causal organism in association with the disease symptoms.[1]SKELETONIZER(S) - Insects which consume leaf tissue, often from the lower side of the leaf, leaving the upper epidermis and vascular tissues intact.[1]SPORE - A specialized structure consisting of one or few cells and serving any or all of the following three functions: (i) reproduction, (ii) dissemination. (iii) survival.[1] Fin. Swe.SPOROPHORE - A spore-producing or supporting structure.[1] Fin. Swe.STADIUM (plural = stadia) - The period of time between two successive molts.[1] Fin. Swe.STAGE - One of the successive principal divisions in the life cycle of an insect, e.g., egg, nymph, larva, prepupa, pupa, adult.[1] Fin. Swe.STAGHEAD - Death of limbs and main branches of a tree in the upper crown, giving the appearance of antlers.[1] Fin. Swe.STIPPLE - Pigmented spots up to a few millimeters in diameter, often on the upper surface of leaves.[1]STYLET - A small, stiff, needlelike tube inserted into a food source to obtain liquid food.[1]SUCKING INSECTS - Insects that insert their mouthparts into plant tissues and withdraw nutrients and fluids through stylets.[1] Fin.SUSCEPT - Any organism that can be attacked by a biotic pathogen.[1]SYMPTOM - Visible or measurable manifestation that an organism is diseased; a change in the organism itself.[1] Fin. Swe.

TTELIAL STAGE (telium) - A stage of the rust fungi; a fruiting structure usually appearing as fine, hairlike projections from lower surfaces of infected leaves.[1] Fin. Swe.THORACIC - Belonging or attached to the thorax.[1] Fin.

THORAX - The body region behind the head, which bears wings and true (jointed) legs if present.[1] Fin. Swe.TUFT - Bunching of twigs or needles.[1] Fin. Swe.TYLOSIS - Outgrowth of a cell membrane from a ray or axial parenchyma cell through a pit in a xylem vessel wall into the vessel, partially or completely blocking the lumen of the vessel.[1]

UUREDIAL STAGE (uredium) - A stage of the rust fungi; a fruiting structure usually appearing as a pustule bearing the repeating spore stage that leads to disease increase. Fin. Swe.

WWATER-SOAKED - A dull green coloration of diseased tissues due to membrane leaking of cellular contents into intercellular spaces.[1] Fin. Swe.WILT - A common symptom of disease due to a loss of turgor and resulting in subsequent drooping and collapse of the foliage or succulent tissues.[1] Fin. Swe.WITCHES' BROOM - A massed proliferation of the branches of a woody plant.[1] Fin. Swe.

ZZONE LINE - Narrow brown or black lines in decayed or decaying wood.[1]

Absorption (a) In physiology: a process by which nutrients move from the lower digestive tract (small and large intestine or colon) into the blood stream to be utilized by the body. (b) In spectroscopy: the interaction between atoms and radiation (light, X-rays, UV, infrared), where some of the energy of the radiation is absorbed by the electrons of the atoms, increasing their energy content. The loss of intensity of the radiation (e.g. reduced light intensity) can be measured and is an indicator of the structural state of the molecules that absorb the radiation.Action PotentialA spontaneous self-propagating change in membrane potential that travels as a 'wave' along electrically excitable cell membranes found in neurons and muscle cells. Action potentials are triggered when the cell's membrane potential depolarizes (i.e. becomes more positive with respect to the internal side) beyond a threshold value of usually -40mV. Voltage sensitive ion channels (Na and K channels) open and close in fast succession causing first in influx of sodium ions (making the inside more positive = depolarization) followed by potassium efflux (making the outside more positive and inside more negative = hyperpolarization). The potassium efflux brings the membrane potential below the threshold and thus to rest. A new action potential can only be triggered with a new stimulus which comes from neurotransmitter activated ion channels at locations of synaptic interaction between neurons or neurons and muscle cells.AdaptationA process in biological evolution as the result of natural selection where a species becomes better adjusted to the living conditions of its environment (temperature, food sources, and predators). In adaptation, individuals that have the most offspring contribute more of their genetic makeup to the next generation. Beneficial traits are favored in this editing process and the next generation of a species or population (for instance a smaller geographical subset of a species) is better adapted to new environmental conditions that caused certain individuals to have fewer offspring. Thus genes that are not optimal for certain conditions will become rarer as a result. Adaptation, as evolution in general, is studied at the level of a population of interbreeding individuals.Adult Stem CellA specialized cell that is needed for growth, wound healing and tissue regeneration. Adult stem cells are found in all tissues and organs of animals and plants.AlleleThe genetic variant of a gene. A gene can be found in different variants in a population, even in the same individual. Alleles are responsible for the different traits of certain characteristics, such as eye and hair color in animals, and flower and seed color in plants. Alleles are also responsible for genetic diseases.Amino AcidBuilding block of proteins and enzymes. Dietary proteins need to be broken into their amino acid components before they can be used by the body. Note that there are 20 amino acids found in proteins. Many nutritional lists describe only 18 occluding glutamine and asparagine. Their values are included in those reported for the acidic forms glutamate and aspartate.AnabolismBiosynthesis of molecules in cells and part of metabolism.

AntioxidantA molecule that protects cells from oxidative damage of oxygen and free radical molecules that are chemically unstable and cause random reactions damaging proteins, nucleic acids, and cell membranes. Examples of dietary antioxidants are vitamins C, E, and K, and diverse plant products such as lycopene, a nutraceutical found in tomatoes.Aperiodic Refers to the lack of symmetry in molecular structures or functions. An important insight into the mechanism of biological structures is their aperiodic composition and distribution of atoms causing the extraordinary complexity of cells.ArchaeaA prokaryotic form of life that forms a domain in the tree of life. There are three domains: bacteria, archaea, and eukarya. Bacteria are also prokaryotic organisms. Eukaryotes include animals, plants, fungi, and protozoan and have very different cell structures, bigger and with internal membrane bound structures (organelles). While bacteria and archaea look similar in structure, they have very different metabolic and genetic activity. One defining physiological characteristic of archaea is their ability to live in extreme environments. They are often called extremophiles and unlike bacteria and eukarya depend on either high salt, high or low temperature, high pressure, or high or low pH.Atom (atomistic) The smallest unit of matter as recognized by chemical properties of molecules. Atoms are composed of protons, neutrons and electrons. The latter provide all properties described by molecular interactions and chemical reactions that are essential processes in biology.ATPShort for Adenosine triphosphate, a nucleotide and universal energy currency for metabolism. Almost all caloric content of food is converted into ATP before it can be utilized for tissue growth, muscle work and other physiological processes.AxonThe cell extension of a neuron (nerve cell) that carries an electrical signal to synapses which are secreting chemical signaling molecules called neurotransmitters to stimulate/inhibit receiving cells. Some axons in the peripheral nervous system connecting to muscle cells or connecting sensory neurons from the skin, eye, or internal organs to the central nervous system can be quite long (measure in centimeters; 1 inch = 2.54 cm) compared to the size of an average cell (measured in micrometers).Bacteria Single cell organisms and most prevalent form of life on Earth. Bacteria are also known as prokaryotes (together with archaea; formerly archaebacteria) referring to the single compartment inside the cell and missing a membrane delineated cell nucleus found in all eukaryotes. Examples are Escherichia coli (E.coli), Salmonella typhimurium (S. typhi), Mycobacterium tuberculosis (M. tuberculosis), or Helicobacter pylori (H. pylori).Bad cholesterolSee Cholesterol, Lipoprotein.BileThe digestive juice released from liver (stored in gall bladder) into the digestive tract to help solubilize and absorb fat soluble nutrients. Bile contains bile acids, biochemical derivatives of cholesterol. Bile acids serve as intestinal detergents for the proper homogenization and uptake (absorption) of dietary lipids.BiodegradableA property of molecules or chemicals that refers to their usefulness as food because they can be metabolized (metabolism) by organism.BiodiversityThe collective richness and variety of all forms of life - bacteria, archaea, eukarya and associated viruses.BioelectricityThe term bioelectricity refers to the use of charged molecules and elements (= ions) in biological systems. The movement and placement of charges has a great influence on molecular interactions between molecules and thus affects structure and function of proteins, DNA, and cell membranes. The latter are able to stabilize local charge separation in form of ion gradients which are a form of energy storage but also serve as information processing device (see action potential).Biological value (of proteins)The biological value of a protein refers to the how much of the nitrogen content of food is retained by the body. The biological value of proteins ranges from 50 to 100 percent and is a measure of how much dietary protein source can support growth. Animal proteins have biological values of 70 percent or higher, and plant proteins have biological values of 50 to 70.BiopharmingA new filed in agriculture using recombinant DNA technology to

introduce genes into plants or livestock for the purpose of expressing a drug or nutrient in quantities not found in nature. Biopharming may be used to produce antibodies in cow milk or hormones in plant leaves or seeds for easy harvesting. The plant or animal serves as a natural bioreactor and has become a genetically modified organism in the process.Biotechnology Application in biology to manipulate the structure and function of biological systems into forms not found in nature. Often used to improve or facilitate cellular processes such as energy metabolism, gene transfer between unrelated species, or the engineering of enzymes for the large scale synthesis of drugs. Carbohydrates Biochemical name for sugar containing molecules including single sugar (monosaccharides) like glucose and galactose, but also polysaccharides (complex carbohydrates) like starch (poly-glucose), cellulose (plant fiber material, also poly-glucose with a different chemical bond structure linking glucose units than those found in starch/glycogen and enzymatically indigestible by humans), chitin (hard shells of insects), and more complex carbohydrate components part of lipids and proteins such as blood serum glycoproteins (antibodies and blood group determinants A, O, B, rhesus positive or negative). All microorganisms (bacteria, viruses) contain carbohydrate surfaces (glycolipids) being the major determinants of immunogenic reactions during infections.CarbonThe element that defines the chemical properties of all life. All molecules that contain carbon are known as organic molecules and studies by organic chemistry. Carbon is the third most common element in cells, after hydrogen and oxygen, which are the most common biological elements because they are found in water. Also water makes up to 70% of a cells weight, it is not an organic molecule, since it lacks carbon.Calorie (Cal)Chemical energy in foods is expressed in calories (Cal). The scientific definition of a calorie is the amount of energy needed to raise the temperature of 1 gram of water by one degree Celsius from 15° to 16° at atmospheric pressure. This is the true calorie, sometimes referred to as a "small calorie". A kilocalorie is equal to 1000 calories. In reference to food energy, the term "calorie" is actually a 1,000 calories or 1 kilocalorie. The USDA Nutrient Database for Standard Reference contains values for both kilocalories and kilojoules (1 kcal equals 4.184 kJ).CapacitanceAn element (capacitor) in an electrical circuit capable of separating charges and storing electrical energy. In cells, membranes have capacitor properties contributing to the storage of electrochemical energy (ion gradients).CatabolismThe part of metabolism responsible for degradation of nutrients and energy extraction for the benefit of ATP production.Cell Smallest unit of life (single cell organism or bacteria) or unit of higher organisms, i.e., multicellular organisms. Cells are surrounded by a cell membrane (and cell wall in bacteria and plants = a membrane plus some chemically more stable structures, often mixtures of proteins and polysaccharides) and contain all necessary elements to sustain life; proteins, nucleic acids, lipids, minerals, and a diverse class of metabolites. Cells of higher organisms (known as eukaryotes) are subdivided into subcellular compartments called organelles such as the mitochondrion, the cell nucleus, the endoplasmatic reticulum, the Golgi apparatus and many smaller organelles with highly specialized functions. While all these organelles are found in animal cells, plant cells in addition contain a central vacuole that controls pressure to stabilize the cell and chloroplasts, the site of photosynthesis or light depended biosynthesis of sugars (carbohydrates).Cellular automatonA program the applies a simple rule of what to do repeatedly. Depending on the rule of what to do next, the pattern or behavior generated can look (i) repetitive, simple, and symmetric, (ii) nested (fractal), (iii) random and without any symmetry or repetition whatsoever, or (iv) complex with local patterns but overall broken symmetry (see also complexity).Channel (Ion Channel)A membrane protein that allows the passive flow of ions across a cell membrane. Ion channels are usually selective for a specific ion type (e.g. Na, or K, or Cl, or Ca) and or either open or closed. These are two structural states of the protein and the change from the open to the closed state (gating) is regulated by the cell. Several regulatory mechanisms have been described including voltage-gating, ligand-gating, heat, and mechano-sensation (touch sensitive). Channels are a category of transporters.

Cholesterol Important lipid found only in animals. Cholesterol is important as cell membrane component, but also serves as a biosynthetic precursor for steroid hormones (e.g. sex hormones) and the active gall bladder ingredients bile acids (= detergents). The human liver can synthesize all the necessary levels of cholesterol and will reduce its own synthesis if cholesterol is taken in during a meal (only from animal sources). 'Bad' and 'Good' cholesterol refers to special transport particles of lipids in our blood serum called lipoprotein particles. The low density form or LDL is high in cholesterol and chronically high concentration of LDL in blood results in insoluble deposits that can clog arteries and restrict blood flow contributing to heart problems.ChromosomeThe physical unit of genetic material in a cell. Prokaryotes have usually one large circular chromosome and one or more small circular extra-chromosomal DNA (plasmids). Eukaryotic cells have often several to several dozen chromosomes. Humans have 46 chromosomes comprising two sets of 23 chromosomes. Each set constitutes the complete human Genome carrying approximately 35,000 genes. Each chromosome carries between 1,000 to 2,000 genes. Eukaryotic chromosomes are linear, long DNA molecules tightly packed with proteins that control their structure and activities of genes.ChymeDigested content of the stomach released for further digestion in the small intestine.Clone, cloningA clone is a genetic copy of a parent cell or organism. Cloning is the process of producing a genetically identical offspring or copy. Cloning is a natural process that underlies asexual reproduction that include the binary fission of prokaryotic cells (bacteria and archaea) and mitotic cell division of eukaryotic cells. Mitosis occurs continuously in the human body due to growth and tissue repair (wound healing) and maintenance (skin regeneration, hair growth). Cloning can also refer to the technical process of duplicating genetic material in the laboratory, for instance through the polymerase chain reaction (PCR).Co-Enzymes or Co-FactorsNon-protein substances necessary for the function of some enzymes. Essential coenzymes are also known as vitamins.Code (genetic)The genetic code is the information needed to translate a nucleic acid (gene) sequence into an amino acid (protein) sequence. The code consists of triplet structures called codons such as UUG meaning two uracil and one guanine base along the messenger RNA template. This codon is recognized through base pairing by an anti-codon (triplet) on a transfer RNA. The transfer RNA is a specialized small ribonucleic acid that identifies genetic sequences on messenger RNAs (with the help of ribosomes) and carries one specific amino acid. An amino acid always matches one particular anti-codon. There are twenty amino acids to choose from for protein synthesis, and a total of 64 triplet codons (four bases in triplet sequence = 4x4x4 combinations). Thus there are 64 codons to match 20 amino acids, which means that some amino acids are coded by more than one codon. Which codons are responsible for which amino acid is evolutionarily conserved and most organisms have the same code or translation table. There are some alternate assignments found in mitochondrial genomes, viral genomes and some bacterial genomes. Yet, the fact that most organisms, bacteria, archaea and eukarya use the same genetic code explains the ability for recombinant DNA technology, i.e., to cut and past genetic elements from one organism into an other organism, since the assign amino acids to the same codons. Thus a human gene can be expressed in bacteria or yeast or jelly fish, and jelly fish genes can be expressed in bacteria, plants, fungi, animals and protists. There are almost limitless combinations possible. Read more about genetic codes at the National Center for Biotechnology Information and see the standard genetic code for humans and most organisms.Cognitive, cognitionCognition refers to the physical recognition of external stimuli that lead to conscious experiences.ComplexityComplexity is the measure of the number and strength of interactions of its components. The components are organized not in a linear chain, but a network with specific connectivity, branches and loops. Network components affect each other through their interactions (molecular interactions). Complexity in biology is the result of dynamic interactions that follow each other in time and with both forward and feedback loops. Because of loops, the output of a network will affect a future input, thus continuously adjusting the physical output value of the system. Biological networks have evolved as stable systems. Stability means that biological systems are

in homeostatic equilibrium, with information constantly flowing through the system and the output kept within a narrow range.ConductanceConductance refers to the flow of ions (charges molecules and elements and measured in 'Siemens') such as sodium, potassium, and chloride and is the proportionality factor relating current to a voltage difference. In electricity theory conductance is the inverse of the resistance as defined by Ohm's law V = RI, where V is the voltage, R the resistance, and I the current).Connectome The totality of all neuronal connection in the brain of an animal.CovalentThe chemical bond between atoms.Crystal In biology refers to large, regular assembly of macromolecules such as proteins and nucleic acids. It is possible to isolate and purify proteins or DNA in large quantity and let them crystallize in saturated solution. These protein or DNA crystals contain millions of regularly aligned units that allow the determination of the electron distribution from X-ray diffraction studies. Since atoms are distinguished by their specific numbers of electrons, their distribution allows an analysis of the atomic composition of proteins or DNA. This electron distribution is then used to calculate the so called high resolution structure of molecules.CytoskeletonA fibrous network made of proteins that contributes to the structure and internal organization of eukaryotic cells. The cytoskeleton is found in the cytoplasm of cells and has three major fiber types: microfilaments made of actin protein, intermediate filaments made of various kinds of proteins (e.g. keratin), and microtubules made of tubulin. The three fiber types serve different functions; actin filaments are often associated to changes in cell size and structure, contractility such as in muscle cells, and cell division, growth and motility. Microtubules are major filaments for internal transport and movement of chromosomes and organelles during cell division. Intermediate filaments contribute to flexibility, elasticity, and stiffness of cells and tissues. EcosystemA specific characteristic biological system in a location or area with a unique mix of living organisms and physical consistency such as minerals, soil and air.ElementAn atom with a unique number of protons (atomic number). There are 102 different elements and some additional synthetic elements that are not found in nature. Elements have different physical and chemical properties and can be combined to molecules (two or more atoms linked through covalent bonds). The elements are listed according to atomic number and chemical properties in the  periodic table.GlucoseThe major carbohydrate in starch and fruit sugar. The latter is also known as sucrose and contains fructose with every glucose molecule.HypothesisA testable scientific idea that can be proved right or wrong with experiments. A hypothesis is a formulation of a question that lends itself to a prediction. This prediction can be verified or falsified. A question can only be use as scientific hypothesis, if their is an experimental approach or observational study that can be designed to check the outcome of a prediction. Macronutrients Also called caloric nutrients including proteins, carbohydrates, and fats. Some definitions include water and alcohol. The term is used by gardeners and in agriculture referring to common minerals needed for proper plant growth.Nutrient Molecules that can be used by cells or living organism to extract energy through metabolic processes. Although nutrients are often sought off only as energy providers, they can also be used as molecular building block for the biosynthesis of cellular structures. Organelle Subcellular structure in eukaryotic cells (e.g. plants and animals) providing specialized function within cells. Organelles are separated from each other and the cytoplasm of the cell by membranes.Organic Compounds that contain carbon, such as vitamins, carbohydrates, proteins and fats, but not minerals. Organic is a chemical term designating compounds containing a carbon skeleton plus hydrogens, oxygen, and in smaller and variable amounts nitrogen, phosphorus, or sulfur.Population The totality of a closely related number of individual organisms that belong to the same species and live in the same geographical area and

interact with each other through sexual (or asexual for bacteria) reproduction.Protein Proteins are macromolecules made from twenty different types of amino acids. Proteins constitute the active component of cells . Proteins function as enzyme in metabolism, transporters and receptors in cell membranes, hormones, antibodies, and help read, translate, and replicate the genetic information. Recessive traitThe quality of a gene or allele regarding its ability to express a phenotype.Statistics The mathematical procedure to describe probabilities and the random or non-random distribution of matter or occurrence of events.TaxonomyTaxonomy is the classification of organisms according to their evolutionary relationship. Taxonomic groups are organized in a hierarchical fashion from the most inclusive domains of life (archaea, bacteria, eukarya, viridae) to the lowest most specific species description (e.g. Homo sapiens).TheoryA scientific theory is an established and experimentally verified fact or collection of facts about the world. Unlike the everyday use of the word theory, it is not an unproved idea, or just some theoretical speculation. The latter meaning of a 'theory' in science is called a hypothesis.GlossaryAbiotic - The non-living components of the environment, such as air, rocks, minerals, water, coal, peat, plant litter, etc.Absorption - The process by which a solution passes from one system to another, e.g., a herbicide passes from the soil solution into a plant root cell or from the leaf surface into the leaf cells.Achene - Small, dry, one-seeded fruit.Acid soil - A soil having a preponderance of hydrogen ions (low pH) over hydroxyl ions (high pH) in the soil solution; thus a soil with a pH below the neutral range (pH 6.6 to 7.3).Acre - An area of land containing 43,560 square feet, roughly the size of a football field, or a square that is 208 feet on a side.Active ingredient (ai) - The chemical in a herbicide formulation primarily responsible for its phytotoxicity and which is identified as the active ingredient on the product label.Acuminate - Having a leaf tip whose sides are concave and tapering to an elongated point.Acute - Leaf shape, having margins tapered to a point.Adjuvant - Any substance in a herbicide formulation or added to the spray tank to modify herbicidal activity or application characteristics.Adsorption - The process by which an ion (or charged particle) in a solution bonds to a charged surface, e.g., a herbicide adheres to a soil colloidal surface like clay, or organic matter.Adventitious bud - A bud which develops at the base of a needle cluster, on a root, or on woody tissue on a branch or leader, when the end of the branch or leader is injured or cut off.Afforestation - Establishing a forest on an area which has not previously had trees growing on it.Alkaline - Referring to soil pH of 7.0 and higher, performance of some tree and shrub species is affected in these soils because needed nutrients e.g., iron, become insoluble and unavailable to the plant.Alkaline soil - Soil having a preponderance of hydroxyl ions (high pH) over hydrogen ions (low pH) in the soil solutions; thus a soil with pH above the neutral range (6.6 to 7.3).Allelopathy - The adverse effect on the growth of plants or microorganisms caused by the action of chemicals produced by other living or decaying plants.Alternate - Bud or leaf arrangement (singly) along a stem at spiraled intervals.Annual ring - The growth layer of one year, as viewed on the cross section of a stem, branch, or root.Antagonism - An interaction of two or more chemicals such that the effect when combined is less than the predicted effect based on the activity of each chemical applied separately.Anther - The pollen containing part of a stamen.Anthracnose - A disease usually characterized by ulcer-like leaf or fruit spots and caused by fungi that produce asexual spores in the type of fruiting body called an acervulus.Apiculate - Ending abruptly in a short-pointed leaf tip.Appressed - Lying close and flattened against.Aquifer - A sand, gravel, or rock formation capable of storing or conveying water below the surface of the land.Arcuate venation - To arch or curve like the veins in dogwood (Cornus).Ascending - Rising somewhat obliquely and curving upward.Astringent - Pungent, strong odor or taste.

Awl-shaped - Oval shaped, with sharp pointed end, e.g., juniper leaves.Axillary - Pertaining to the area where the leaf petiole and stem are connected or the axil.Band treatment - Applied to a linear restricted strip on or along crop rows rather than continuously over the field area.Basal treatment - Applied to encircle the stem of a plant just above the soil surface such that foliage contact is minimal. A term used mostly to describe treatment of woody plants.Bedrock - Unbroken solid rock, overlain in most places by soil or rock fragments.Biological control - The use of organisms or viruses to control parasites, weeds, or other pests.Biosphere - The part of Earth's surface, soil, water and its immediate atmosphere occupied by living organisms.Bipinnate - Twice pinnate (as in honey-locust leaves).Blade - The broad, flat, green part of the leaf.Bole - The main trunk of a tree.Bract - A modified leaf from the axil of which a flower or flower cluster arises.Broadcast treatment - Applied as a continuous sheet over the entire field.Broad-elliptic - Wider than elliptic.Browse - Portions of woody plants including twigs, shoots, and leaves used as food by such animals as deer.Browseline - The uppermost limit on trees and tall shrubs to which livestock and big game animals browse. (syn. grazing line.)Browser - Large mammals that feed on the young growing parts of trees or shrubs.Buttressed - Broadened base or arched root flare of the trees trunk.Calcareous soil - Soil containing sufficient free calcium carbonate (lime) or calcium-magnesium carbonate (dolomite) to effervesce visibly when treated with cold 0.1 M HCl in water.Calyx - Outermost whorl of modified leaves in a flower, usually green, but sometimes showy colored.Cambium - The layer of cells between the inner bark and wood of a tree where cell division takes place.Candle - The new bright green and tender shoot growth all conifers produce in the spring.Canopy - The upper level of a forest, consisting of branches and leaves of taller trees.Capsule - A fruit structure consisting of two or more chambers.Catkin - A scaly-bracted spike of unisexual flowers.Cell - The basic structural unit of all living organisms. An organism may be composed of a single cell (e.g. bacteria) or many cells working together (all "higher" organisms, including man).Chaffy - Covered with small thin, dry scales.Chemical name - The systematic name of a chemical compound according to the rules of nomenclature of the International Union of Pure and Applied Chemistry (IUPAC), Chemical Abstracts Service, or other organization.Chemical tolerance - Ability to continue normal growth or function when exposed to a potentially harmful agent (there is no general agreement as to the distinction between herbicide tolerance and herbicide resistance in plants).Chlorosis - A leaf symptom due to mineral deficiencies where the leaf will remain green next to the veins and become yellow from the margins inward.Chlorophyll - The green photosynthetic substance in plants which allows them to capture solar energy.Ciliate - Fringed with hairs on margin.Clay - Soil particles less than .002 mm in size.Clone - A plant group derived from a single individual through vegetative reproduction. Example: A clone of many aspen trees may sprout from the roots of a single aspen tree, after it is cut.Co-Dominant - A tree receiving full light from above, but comparatively little from the sides. Such trees usually have medium sized crowns.Community - The populations of species living in a common ecosystem.Compatibility - The characteristic of a substance, especially a pesticide, of being mixable in a formulation or in the spray tank for application in the same carrier without undesirably altering the characteristics or effects of the individual components.Competition - The active acquisition of limited resources by an organism which results in a reduced supply and consequently reduced growth of other organisms in a common environment.Compound - A leaf that is made up of more than one leaf blade, termed leaflets.Compressed stone - Flattened stone.Concentration - For herbicides, the quantity of active ingredient or parent compound equivalent expressed as moles or mass per unit volume or per unit mass of the resulting solution or mixture.

Expressions of percent should be avoided or used only for expressions of mass per mass.Conical - Cone-shaped.Conifer - A tree belonging to the Order Coniferales which is usually evergreen, cone-bearing and with needle, awl or scalelike leaves such as pine, spruce, fir and cedar; often referred to as a "softwood."Coniferous - Cone bearing trees and shrubs.Connate - Like parts fused together into one.Conservation - The protection, improvement, and use of natural resources according to principles that will assure their highest economic and social service.Contact herbicide - A herbicide that kills primarily by contact with plant tissue rather than as a result of translocation; only the portions of the plant which actually come in contact with the chemical are affected.Convex - Curved like the outer surface of a sphere.Coppice - To regrow wholly or mainly from sprouts.Corymb - Flat-topped or convex flower cluster, outer flowers opening first.Crenate - Toothed with round, shallow teeth.Crown - The branches and foliage of a tree, the upper portion of a tree.Crown classification - Individual trees in a stand may be classified according to the relative size and height of their crowns compared to other trees in the stand. In descending order of crown height and size the classes are: dominate, co-dominate, intermediate, suppressed.Crown cover - The canopy of green leaves and branches formed by the crowns of all trees in a forest. (syn. leaf canopy.)Cultivar - A cultivated variety as distinguished from a botanical variety.Cuneate - Wedge-shaped.Cyme - Flat-topped flower cluster, central flower opens first.Damping-off - The killing of young seedlings by certain fungi that cause decay of the basal stem or roots.Deciduous - Not persistent, leaves falling in autumn.Decurrent - Spreading branches, lack of central leader.Defoliation - The loss of leaves or foliage on a plant or tree.Defoliant - A chemical that causes the leaves to fall from a plant.Dehiscent - Splitting open along seed capsule or pod to emit individual seeds.Dentate - Teeth along leaf margins are pointed outward.Den tree - A hollow tree used as a home by a mammal.Desiccant - Any substance or mixture of substances used to accelerate the drying of plant tissue.Dicotyledon (dicot) - A member of the Dicotyledonae; one of two classes of angiosperms usually characterized by the following: two seed leaves (cotyledons), leaves with net venation.Dieback - The progressive dying, from the tip downward, of twigs, branches or tops.Dioecious - Male and female flowers on separate plants.Directed application - Precise application to a specific area or plant organ such as to a row or bed or the leaves or stems of plants.Dispersible granule (DG) - A dry granular formulation that will separate or disperse to form a suspension when added to water.Dominate trees - Those trees within a forest stand which extend their crowns above surrounding trees and capture sunlight from above and around the crown.Doubly serrate - Many large and small serrations along the leaf margin.Drupe - Fleshy fruit with a pit or stone.Drupelet - A small drupe.Ecosystem - An ecological entity consisting of the biotic community and the nonliving environment functioning together in an inseparable interacting system.Ecotype - A population within a species that has developed a distinct morphological or physiological characteristic (e.g. herbicide or biotic pest resistance) in response to a specific environment and that persists when individuals are moved to a different environment.Edge - The boundary between open land and woodland or two other ecological communities. This transition area between environments provides valuable wildlife habitat.Elliptic - Longer than wide with rounded ends, like an ellipse.Emulsifiable concentrate (EC) - A single phase liquid formulation that forms an emulsion when added to water.Emulsifier - A substance that promotes the suspension of one liquid in another.Endocarp - The inner layer of the pericarp of a seed, e.g. stone fruit.Entire margin - Unbroken, without teeth or lobes.Environment - The sum total of all biological and physical factors affecting an organism, population, or community.Epicormic branching - Branches which grow out of the main stem of a tree, arising from buds under the bark. Severe epicormic

branching increases knottiness, thereby reducing the quality of lumer sawn.Epidemic - A temporary widespread outbreak of disease.Erose - Irregularly toothed or eroded.Erosion - Detachment and movement of soil or rock by water, wind, ice, or gravity.Evergreen - Trees which retain green foliage throughout the year. Not all conifers are evergreens. An example is larch, a deciduous conifer.Excurrent - Tree growth is pyramidal, similar to spruce tree, central leader.Exfoliate - The natural habit of trees for the bark to peel off in shreds or thin layers.Fascicle - A small bundle, e.g., 2 to 5 needles per cluster in pines.Filament - Portion of the stamen comprising the stalk.Fireblight - Bacterial disease causing leaves of susceptible plants to blacken but remain attached to the twigs. Affects pear, apple, crabapple, cotoneaster and mountain-ash.Firebreak - A natural or constructed barrier utilized to stop or check fires that may occur or to provide a control line from which to work. Sometimes called a fire lane.Fissures - Pertains to furrows created in bark as the tree grows.Flowable (F) - A two-phase formulation containing solid herbicide suspended in liquid and that forms a suspension when added to water.Foliage - Growth of leaves on a tree or other plant.Follicle - A dry, dehiscent fruit developed from a simple ovary and splitting along one suture.Forb - Any herbaceous plant other than grass on a prairie site.Fork - A defect characterized by division of the main stem or bole of a tree into two or more stems.Frill treatment - Placement of a herbicide into a series of overlapping ax cuts made through the bark in a ring around the trunk of a tree.Frost crack - A vertical split in the wood of a tree, generally near the base of the bole, from internal stresses and low temperatures.Furrowed - Having longitudinal grooves or fissures.Gall - A pronounced swelling or outgrowth on a plant.Girdling - To encircle the stem of a living tree with cuts that completely sever bark and cambium.Glabrescent - Becoming hairless at maturity.Glabrate - Nearly glabrous or becoming glabrous with age.Glabrous - Without hair, smooth.Glandular - Small, usually shiny bumps on the surface.Glaucescent - Slightly glaucous.Glaucous - Covered with a waxy bloom or whitish material that rubs off readily.Globose - Spherical.Granular (G) - A dry formulation consisting of discrete particles generally <10 cubic mm and designed to be applied without a liquid carrier.Growth rate - With reference to wood, the rate at which the wood substance has been added to the tree at any particular point; usually expressed in terms of number of rings per inch. Growth rate bears an inverse relationship to number of rings per inch. Also applies to volume, value, or other types of increase in trees or stands.Growth rings - The layers of wood laid down each growing season, also called annual rings. These rings frequently are visible when a tree is cut and may be used to estimate the age of the tree, as well as to determine the rate of its growth.Hardwood - A term used to describe broadleaf, usually deciduous, trees such as oaks, maples, ashes, elms, etc. It does not necessarily refer to the hardness of the wood.Heartwood - The inner core of a woody stem, wholly composed of nonliving cells and usually differentiated from the outer enveloping layer (sapwood) by its darker color.Heel-in - To store young trees prior to planting by placing them in a trench and covering the roots or rooting portions with soil.Herbaceous - Lacking a persistent stem above ground dying back in fall.Herbaceous vegetation - The low-growing, non-woody plants in a forest understory, including wildflowers and ferns.Herbicide - A chemical which kills herbaceous (non-woody) plants. In common usage, however, often used interchangeably with the words phytocide (plant killer) and silvicide (tree killer).Herbicide resistance - The trait or quality of a population of plants within a species or plant cells in tissue cultures of having a tolerance for a particular herbicide that is substantially greater than the average for the species and that has developed because of selection for naturally occurring tolerance by exposure to the herbicide through several reproductive cycles.Hispid - Covered with bristly hairs.Horizon, soil - A layer of soil approximately parallel to the land surface with more or less well-defined characteristics that have been

produced through the operation of soil forming processes. 1) A-Horizon: the upper horizon of the mineral soil, which features an accumulation of humified organic matter intimately associated with the mineral fraction. 2) E-Horizon: a light-colored horizon of maximum leaching. 3) B-Horizon: the horizon of accumulation to which materials such as clay, carbonates or iron oxides have been added by percolating waters. 4) C-Horizon: the weathered soil parent material.Humus layer - The top portion of the soil which owes its characteristic features to its content of humus. The humus may be incorporated or unincorporated in the mineral soil.Hybrid - A sexually produced cross between two closely related species.Imbricate - Overlapping, like shingles on a roof.Imperfect (flower type) - Lacking stamens or pistils, but not both.Impressed - Bent inward, furrowed as if by pressure.Inconspicuous - Small, not readily noticed by the naked eye.Incorporate - To mix or blend a herbicide into the soil.Incurved - Curved inward.Infiltration - The downward entry of water into the soil. This is distinct from percolation, which is movement of water through soil layers or material.Insecticide - Any chemical used to destroy insects and other small invertebrates.Insipid - Lacking taste, smell or quality; dull.Internode - Part of stem between two nodes.Interplant - To set young trees among existing forest growth of similar age and/or size, planted or natural, to bring the stand to a fully stocked condition.Intolerance - The characteristic of certain tree species which does not permit them to survive in the shade of other trees, e.g. aspen and Norway pine are intolerant; sugar maple and balsam fir are tolerant.Invert emulsion - The suspension of minute water droplets in a continuous oil phase.Lanceolate - Lance shaped, broadest at base of leaf blade. Much longer than broad, tapers to the leaf tip.Lateral buds - Those buds below the terminal buds where side branches arise.Layby application - Applied and incorporated with or applied after the last cultivation of a crop.Layering - A method of propagation in which adventitious roots form on a stem while it is still attached to the parent plant. Occurs naturally with some species.LD50 - The dose(quantity) of a substance that will be lethal to 50% of the organisms in a specific test situation. It is expressed in weight of the chemical(mg) per unit of body weight (kg) and the toxicant may be fed (oral LD50), applied to the skin (dermal LD50), or administered in the form of vapors (inhalation LD50).Leaching - Downward movement of a pesticide, fertilizer or other soluble material through the soil as a result of water movement.Leader - A terminal leader is the uppermost branch or vertical tip of the tree. It eventually becomes the tree stem or trunk.Leaflet - A single segment of a compound leaf.Leaf margin - Refers to leaf edge.Leaf scar - The mark which remains where a leaf falls off a twig.Leggy - Pertaining to over growth of trees or shrubs where stem growth is lengthened and weak. Devoid of lateral branches.Lenticel - A breathing pore in young bark, appearing as a light-colored, often lens-shaped, dot, e.g. on birch.Loam - A soil textural class containing 7 to 27% clay, 28 to 50% silt, and less than 52% sand.LRA - Land resource area, designation of soil types within the state or regional boundaries.Machine, planting - Mechanical equipment which opens a hole or furrow and closes it again and firms the soil about a tree seedling which is usually inserted by hand.Macronutrient - A chemical element necessary in relatively large amounts (usually greater than 500 ppm in the plant) for the growth of plants. These elements consist of C, H, O, Ca, Mg, K, P, S, and N.Main stem - The portion of a tree between ground level and the division into major branches, usually referred to as the bole.Malodorous - Bad smelling.Mast - Nutlike fruits of trees, such as acorns, beech, and chestnuts. Mast is valuable as a source of food for many wildlife species.Mature tree - A tree that has reached the desired size or age for its intended use. Size or age will vary considerably depending on the species and intended use.Micro-encapsulated formulation (ME) - Herbicide enclosed in capsules (or beads) of material to control the rate of release of active ingredient and thereby extend the period of activity.Micronutrient - A chemical element necessary only in extremely small amounts (usually <50 ppm in the plant) for the growth of plants. These elements include B, Cl, Cu, Fe, Mn, Mo, and Zn.

Miticide - A chemical that is used to control or kill mites.Monocotyledon (monocot) - A member of Monocotyledonae; one of two classes of angiosperms, usually characterized by the following: one seed leaf (cotyledon), leaves with parallel venation, root systems arising adventitiously and usually diffuse (fibrous).Mortality - Death or destruction of forest trees as a result of competition, disease, insect damage, drought, wind, fire, and other factors.Mottled - An irregular spotting or alternating color on leaves, stems and other plant parts.Mucronate - Abruptly terminated by a short, sharp leaf tip.Mulch - Any material such as straw, wood or bark chips, leaves, plastic film, loose soil, etc., that is spread on the surface of the soil to protect the soil and plant roots from the effects of rain drops, soil crusting, freezing, and evaporation, or to control weeds.Needle - Elongate, linear, sharp-pointed leaf.Node - Joint on a stem, represented by point of origin of a leaf or bud.Nonselective herbicide - An herbicide which will kill or harm all or most plant species.Non-target species - A species not intentionally affected by a pesticide.Noxious weed - A plant defined by law as being especially undesirable, troublesome, and difficult to control.Oblique - Lop-sided, one side of leaf base is larger, wider or more rounded than the other.Oblong - Two to three times longer than broad.Obovate - Inversely ovate.Obovoid - Leaf shape that is inversely egg-shaped or obovate.Obtuse - Rounded, approaching semi-circular.Opposite - Buds or leaves growing in pairs but separated by a stem.Oval - Twice as long as broad, widest at the middle, both ends rounded.Ovate - Egg shaped in outline, narrower at the tip.Overstocked - The situation in which trees are so closely spaced that they are competing for resources, resulting in less than full-growth potential for individual trees.Overstory - The canopy in a stand of trees. In contrast to the understory which is low growing woody or herbaceous vegetation forming a layer beneath the overstory.Overtop application - A broadcast or banded application applied over the canopy of crops such as by airplane or a raised spray boom of ground equipment.Overtopped crown class - Trees with crowns entirely below the general level of the crown cover receiving no direct light either from above or from the sides. (syn: suppressed.)Ovoid - Three dimensional, egg-shaped.Palatable - Appetizing taste, savory.Palmate - With three or more lobes, veins or leaflets arising from one point, often five to seven.Panicles - Loose, irregular compound flower clusters.Pathogen - A living organism capable of causing disease in a particular species or range of species.Pectinate - Like a comb, with many or few narrow pinnate divisions.Peduncle - Primary flower stalk.Pelleted formulation - A dry formulation consisting of discrete particles usually larger than 10 cubic millimeters and designed to be applied without a liquid carrier.Pendulous - Hanging down, drooping.Percolation - The downward movement of water through soil.Perfect (flower type) - Having both functional stamens and pistils.Pericarp - Sometimes used to designate a fruit, technically the ovary wall.Persistent - Hang on through winter or long period of time, e.g. plant parts: fruits, seeds, leaves, etc.Persistent herbicide - A herbicide that, when applied at the recommended rate, harms susceptible crops planted in normal rotation after harvesting the treated crop, or that interferes with regrowth of native vegetation in non-crop sites for an extended period of time.Persistence time - The time required for a pesticide to become inert. Arbitrarily assumed to equal four half-lives when measured persistence time is not available.Pesticides - Chemical compounds or biological agents used for the control of undesirable plants, animals, insects or diseases.Pesticide interaction - The action or influence of one pesticide upon another and the combined effect of the pesticide(s) on the pest(s) or crop system.Petiole - The stalk of a leaf.pH - The measure of the acidity or alkalinity of soil. Descriptive terms commonly associated with certain ranges in pH are: extremely acid <4.5; very strongly acid, 4.5-5.0; strongly acid, 5.1-5.5; moderately acid, 5.6-6.0; slightly acid, 6.1-6.5; neutral, 6.6-7.3;

slightly alkaline, 7.4-7.8; moderately alkaline, 7.9-8.4; strongly alkaline, 8.5-9.0; and very strongly alkaline, >9.1.Phloem - The tissue in higher plants which transports organic nutrients manufactured in the leaves to other portions of the plant.Phytotoxicity - Injury or death of plants due to exposure to a chemical.Pilose - Long, soft hairs.Pinnate - Compound leaf with leaflets on either side of central axis.Pith - Spongy center of a twig; if it has crosswalls, it is called "chambered."Plantation - An artificially reforested area established by planting or direct seeding. Contrast with a natural forest stand which is established naturally.Plant growth regulator (PGR) - A substance used for controlling or modifying plant growth processes without severe phytotoxicity.Planting bar - A hand tool used in making a slit-hole in which trees are planted.Plumed - Feathery.Polygamo-dioecious - Part of flowers are perfect and part are unisexual with male and female flowers on separate plants.Polygamo-monoecious - Sexual condition in which some perfect and staminate flowers are on the same plant.Pome - Fleshy fruit with a core, such as a crabapple.Postemergence (POST) - (1) Applied after emergence of the specified weed or crop. (2) Ability to control established weeds.Preemergence (PRE) - Applied to the soil before emergence of the specified weed or crop.Preplant application - Applied before planting or transplanting a crop, either as a foliar application to control existing vegetation or as a soil application.Preplant incorporated (PPI) - Applied and blended into the soil before seeding or transplanting, usually by tillage.Pruning - The removal of live or dead branches from standing trees. With forest trees, pruning is generally done along the trunk to remove the side branches (which cause knots in the wood) to produce a higher quality wood (knot-free).Pubescent - Covered with short, soft hairs.Racemes - Pedicled flowers along one stem.Range - The geographic area in which a tree species grows.Rejuvenation - Restore to healthy vigorous growth, often through weed control, pruning, fertilization, irrigation or treatment for insects and diseases.Release - To free trees from competition by cutting or otherwise removing or killing nearby vegetation and branches. Usually applied to young stands.Reproduction - The process by which the forest is replaced or renewed. This may be: Artificial Reproduction (by means of seeding or planting); Natural Reproduction (from natural seeding or sprouting.Residual herbicide - A herbicide that persists in the soil and injures or kills germinating weed seedlings for a relatively short period of time after application.Resinous - Sticky with resin.Resistance - Ability to withstand exposure to a potentially harmful agent without being injured (There is no general agreement as to the distinction between herbicide tolerance and herbicide resistance in plants.)Restricted-use pesticide - A pesticide which is designated as such by the Environmental Protection Agency because it is felt that it may generally cause, without additional regulatory restrictions, unreasonable adverse effects on the environment, including injury to the applicator. A "restricted-use" pesticide may be used only by, or under the direct supervision of, a certified applicator.Reticulate - Like a net, netted venation.Revolute - Stem or leaf rolled lengthwise so as to expose the top side and conceal the bottom side.Rhombic - With four nearly equal sides, but unequal angles.Roots - That portion of the tree which is generally underground and which functions in nutrient absorption, anchorage and storage of food and waste products.Rose hips - Fruit containing the ovary and seeds of the Rosa species.Rugose - Rough, covered with wrinkles.Rufous - Reddish brown.Saline soil - A soil condition in which soluble salts are present in the soil in sufficient quantity to affect the ability of certain plants to absorb water from the soil. Trees and shrubs do best on soils with salinity levels below 2.0 deciSiemens per meter (dS/M) or millimhos per centimeter (mmhos/cm). However, many plants are able to perform satisfactorily on soils with salinty levels between 2 to 8 dS/M. Only a limited number of species survive at salinity levels between 8 and 16 dS/M. No species grow well on soils with salinity exceeding 16dS/M. The following chart quantifies the ranges of salinity:

Measurement Range------------------------------------- less than 2.0 not saline 2-4 very slightly saline 4-8 slightly saline 8-16 moderately saline 16+ strongly saline Samara - Dry, one-seeded fruit with a membranous wing.Sand - Mineral soil particles .05 to 2.0 mm in size.Scale - Bud covering or tiny, blunt leaf.Scalping - Removing a patch or strip of sod in preparation for planting trees.Schizocarp - Winged, paired samara-like fruits, e.g. maples.Scurfy - Scaly or flaky on the surface.Sediment - Solid material that is in suspension, or transport, or that has been moved from its original location by wind, water, gravity, or ice.Seepage - Percolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.Selective herbicide - A chemical which is effective only against certain species and is able to control unwanted plants without serious injury to desirable species.Senescence - Refers to old age, decline in older trees.Serrate - Fine, sharp teeth that point upward or forward along the leaf margin.Serrulate - Finely saw-toothed leaf margin.Setose - Leaf margins are covered with bristles.Sessile - With no stalk or petiole.Shade tolerance - Relative ability of a tree species to reproduce and grow under shade. Tree species are usually classified in descending order of shade tolerance as: very tolerant, tolerant, intermediate, intolerant, and very intolerant.Shearing - The operation of cutting off trees and brush at ground level by pushing a bulldozer blade along the frozen surface in winter. The stems and trunks are sheared off at ground level.Shelterbelt - A multi-row wind barrier of living trees and shrubs maintained for the purpose of protecting farmsteads and agroforestry crops by providing wind protection, reduction in energy costs, snow control and aesthetic values.Showy - Attractive, pertaining to aesthetic value.Shrub - A low-growing perennial plant with persistent woody stems and low branching habit.Silt - Mineral soil particles .002 to .05 mm in size.Sinus - The space between lobes.Site - An area evaluated as to its capacity to produce a particular forest or other vegetation based on the combination of biological, climatic and soil factors present.Site preparation - Treatment of a site with mechanical clearing, burning, or herbicides, to prepare a site for planting.Slash - Debris left after logging, pruning, thinning, or brush cutting; also, large accumulation of debris after wind or fire. It includes logs, chunks, bark, branches, stumps and broken understory trees or brush.Slash disposal - Treatment of slash to reduce the fire hazard or for other purposes.Slope - A term of measurement in percent indicating the increase in height over the distance measured. An increase of one foot over a distance of five feet is expressed as a 20 percent slope.Snag - A standing dead tree used by many species of birds and mammals for feeding and nesting.Sodic soil - A soil with a pH of >8.5 that contains sufficient sodium to adversely affect crop production and soil structure. The soil structure has been altered through the dispersion of organic matter and clay particles resulting in a dense layer restrictive to moisture and root growth. The shallow root zone above the sodic layer predisposes plants to drought stress. Sodic soils may be found associated with saline conditions.Softwood - Generally, one of the botanical groups of trees that in most cases have needle or scale-like leaves; the conifers; also, the wood produced by such trees.Soil - (1) The unconsolidated mineral material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. (2) The unconsolidated mineral matter on the surface of the earth that has been subjected to and influenced by genetic and environmental factors of: parent material, climate (including moisture and temperature effects), macro- and microorganisms, and topography, all acting over a period of time and producing a product (soil) that differs from the material from which it is derived in many physical, chemical, biological and morphological properties, and characteristics.Soil amendment - Any substance added to the soil that alters physical, chemical, or biological properties, e.g. gypsum, lime, fertilizers, sawdust, etc.Soil reaction (see pH)

Soil texture - The relative proportion of sand, silt, and clay in the soil.Soluble concentrate (SC) - A liquid formulation that forms a solution when added to water.Soluble granule (SG) - A dry granular formulation that forms a solution when added to water.Soluble powder (SP) - A dry formulation that forms a solution when added to water.Species composition - The mix of tree species occurring together in the same stand.Spot treatment - A herbicide applied to restricted area(s) of a whole unit; i.e., treatment of spots or patches of weeds within a larger field.Spray drift - Movement of airborne spray from the intended area of application.Sprout - A tree that grows from the stump or root sucker of a parent tree, not of seed origin. Basswood is frequently of sprout origin.Spur - A saclike or tubular projection on sepal or petal, or a very short fruiting branchlet on apple, pear, or other woody plants.Stalked bud - Bud whose outer scales are attached to a stalk above the base of the bud axis.Stamen - Male organ in the flower, pollen bearing.Stem - The portion of a tree that supports the branches; also called the bole.Stockade - To fortify or surround.Stoloniferous - Producing runners that root above the ground surface.Stomata - Minute openings on the surfaces of leaves and stems through which gases (e.g., oxygen, carbon dioxide, water vapor) and some dissolved materials pass into and out of plants.Stomatiferous - Many pores on the epidermis of a leaf and appearing as many white dots or nodes.Stone - A hard, one-seeded endocarp of a drupe.Striate - With fine longitudinal lines or ridges.Strobili - Inflorescence marked by scales as in a cone.Subcordate - Nearly heart-shaped.Subglobose - Somewhat or nearly round.Subopposite - A bud/leaf arrangement in which they are close to being opposite from each other, but one is slightly lower than the other.Subsessile - Nearly stalkless.Subshrub - A woody or somewhat woody, perennial, winter-hardy plant. The stems of which annually die back partially or wholly to ground level. Resprouts every spring.Sucker (suckering) - A shoot arising from a root or lower part of the stem of a plant.Sucker - Synonymous with sprout.Sunscald - A type of winter injury in which the bark on the southwest side of a stem, branch, or trunk is killed.Suppressed (see Overtopped, Crown classification) - The condition of a tree characterized by low growth rate and low vigor due to competition with overtopping trees.Susceptibility - The sensitivity to or degree to which a plant is injured by a herbicide treatment.Synergism - An interaction of two or more factors such that the effect when combined is greater than the predicted effect based on the response to the factors applied separately.Taproot - A deep centralized rooting habit of certain tree and shrub species, e.g., oak species.Terminal bud - Bud at the tip or distal end.Ternate - Parts occur in threes.Texture - A somewhat subjective analysis of the tree's appearance from a distance including such characteristics as leaf size, branch angles, branch spacing, symmetry of form, e.g. bur oak is considered coarse while false indigo is considered fine. Deciduous trees may have a fine or medium texture in summer, whereas in winter the bare branches may have a coarser texture.Thinning - Removal of trees in an overstocked stand to give the remaining trees adequate room for growth.Tolerance - The capacity of a tree to develop and grow in the shade of and in competition with other trees. Trees able to grow in full or partial shade are considered "tolerant".Tomentose - Densely woolly, soft hairs and matted.Trade name - A trademark or other designation by which a commercial product is identified.Translocated herbicide - A herbicide that is moved within the plant. Translocated herbicides may be either phloem mobile or xylem mobile. However, the term frequently is used in a more restrictive sense to refer to herbicides that are applied to the foliage and move downward through the phloem to underground parts.Transplant - A tree which has been removed from its original seedbed and replanted one or more times in a nursery.

Tree - A woody plant having a well-defined stem, more or less definitely formed crown and usually attaining a height of at least 10 feet.Trifoliate - Three leaflets per leaf.Trilobed - Three lobed, e.g. leaves or fruit.Trunk - Main stem or bole of a tree.Truncate - Shape of leaf base that attaches to the petiole, ends abruptly, as if cut off.Tuberculate - Bearing tubers, a short, thickened organ.Two-ranked - Appearing to come from only two sides of the twig; not equally distributed around the twig, e.g., elm.Umbel - Flower cluster with peduncles springing from same point.Underplant - To set out young trees or sow seed under an existing stand.Understocked - A stand of trees so widely spaced that, even with full growth potential realized, crown closure will not occur. Understocking indicates a waste of resources, as the site is not fully occupied.Understory - The lesser vegetation (shrubs, seedlings, saplings, small trees) within a forest stand which forms a layer between the overstory and the herbaceous plants of the forest floor.Valvate - Edges coming together without overlapping.Vapor drift - The movement of pesticides as vapor from the area of application after the spray droplets have impinged on the target.Venation - Pertaining to the vein pattern in the leaf blades.Water table - The highest point in a soil profile where water continually saturates the soil on a seasonal or permanent basis.Weed - An unwanted plant.Well stocked - The situation in which a forest stand contains trees spaced widely enough to prevent competition yet closely enough to utilize the entire site.Wettable powder (WP) - A finely divided dry formulation that can be readily suspended in water.Wetting agent - (1) A substance that serves to reduce the interfacial tensions and causes spray solutions or suspensions to make better contact with treated surfaces. (2) A substance in a wettable powder formulation that causes it to wet readily when added to water.Whorl - A group of three or more leaves at a node, e.g. catalpa.Wildlife habitat - The native environment of an animal, ideally providing all elements required for life and growth: food, water, cover and space.Wildlife species - Creatures that are associated with plants, such as insects, mammals and birds.Wildlife value - A rating value of woody plants to wildlife species.Windbreak - One or more wind barrier rows of living trees and shrubs maintained for the purpose of protecting crops, feedlots, roadways, farmsteads, gardens, orchards, etc.Windbreak suitability groups - A guide for selecting the species best suited for different types of soils and for predicting height growth and performance effectiveness.Woody plants - Plants which live longer than two years and have a thick, tough stem or trunk covered with a layer of cork.Xylem - The tissue in higher plants which transports water, dissolved salts, and other materials (e.g., pesticides) from the roots to aerial portions of the plant.shttp://www.metla.fi/metinfo/metsienterveys/info/term-e.htmhttp://academic.kellogg.edu/herbrandsonc/bio111/glossary/glossary.htm, http://www.whatislife.com/glossary.htm