First, let's talk about your lab notebook!

Your lab notebook will be graded as anintegral part of work in the laboratory.

Listen to your TA for details.

To begin our investigation of plants, let's take a look at:

The Flowering Plants are without peer in the PlantKingdom! With estimated taxonomic diversity ofabout a quarter of a million species - with new onesdiscovered every year - no other group of plants evencomes close. The Angiosperms are also the group withby far the greatest morphological disparity. Therange of morphologies and anatomies seen withindifferent flowering plants, including large trees, smallherbs, parasitic plants, epiphytes, aquatics, and evenmarine forms, is simply astonishing.

Equally surprising is the fact that Angiosperms haveattained almost complete ecological dominance inmany terrestrial environments - including the mesictemperate forest surrounding us on the BU campus!However, they have accomplished this dominancedespite being evolutionary newcomers. Although mostmajor groups of vascular plants can be traced to originswithin the Devonian through Permian Periods of thePaleozoic Era, the first convincing fossils of floweringplants date from the Lower (early) Cretaceous(approx. 130 ma).

The late and apparently sudden appearance ofangiosperms in the fossil record is a fact that has caughtthe attention of scientists and non-scientists alike. In the19th Century, none other than Charles Darwinviewed the origin of angiosperms as an "abominablemystery" and their sudden appearance in the fossilrecord without recognizable ancestors a potentialfalsifier to his Theory of Evolution.

In the intervening years, there has been muchsystematic and paleobotanical and research on theproblem of angiosperm origins and their subsequentdiversification. Fossil evidence points to a single originof the group perhaps on the northern Gondwana orsouthern Laurasian supercontinents sometime in theearly Cretaceous. However, some researchersconcerned with the exceptionally high disparity ofangiosperms based on morphological or molecular

data, argue for a much earlier origin. They also suggestthat there existed a period of time during which thegroup is somehow completely missing from the fossilrecord.

After their origin, the fossil record of angiospermdiversification is reasonably clear. The group rapidlyexpanded during the Cretaceous becoming ecologicallyimportant by Upper (late) Cretaceous times. Thisdiversification coincided with a major change in thekinds of dinosaurs present in terrestrial environments,with Triceratops and Hadrosaurs perhapsspecialized in part to take advantage of this new foodresource.

Angiosperm diversification continued in the subsequentTertiary Period after dinosaur extinction, and hascontinued to the Present with, except for potentialdisturbance by humans, apparently no end in sight!

We will look at different aspects of Flowering Plantmorphology, anatomy, reproduction, and diversity inthis and the next lab. Weather permitting, we will tryto spend time outside looking for members of thisgroup on campus.

Be prepared to go into the field by wearingappropriate clothing and shoes!

Consult your textbook for useful descriptions,terminology, and pictures. A guide to material in thelab is provided in the links below:

The Flower

The Floral Formula

Inflorescences & Fruits

Family Identification

download this lab in PDF format

Perhaps, the most recognizable and beautiful feature ofAngiosperms or "Flowering Plants" is the flower!The flower is a highly evolved reproductive shootinvolving a greatly modified stem - the flower axis -bearing structures homologous to leaves, includingsepals & petals. Compared with Pteridophytes andGymnosperms, the flower can also be termed abisporangiate stobilus - a structure in which bothmicrosporantiate (pollen) and megasporangiate(ovule/seed) portions of the life cycle are borne togetherwithin the same compact more-or-less "cone-like"strobilus.

Although all flowers are comprised of similar parts,their diversity in form and function is amazing! Asdiscussed in lecture, this diversity is partly the result ofecological and behavioral factors related to pollination- termed pollination syndromes. Some flowers arehighly specialized for wind or water pollination.Others have been designed by evolution to interact withone or more insect, bird or mammal pollinators.Some flowering plants are generalists capable of beingpollinated by a variety of pollinators, whereas othersare specialists - some with specificity between plantand animal that is almost beyond belief!

There is also a strong phylogenetic component toflower morphology. Flower form is the single mostimportant suite of characters utilized in recognizingimportant natural groups of angiosperms at theFamily level. To do this, one needs to becomethoroughly proficient at "diagnosis" of flower form.

As instructed by your TA, obtain a flower of either amonocot or dicot angiosperm. Take it back to your labspace and observe carefully by eye and using adissection microscope. Identify the parts including:

pedicelreceptaclecalyx & sepalscorolla & petalsandroecium & stamensgynoecium

Draw and label all the parts you see. Now concentrateon the gynoecium. In some flowers, there is a single

structure:

pistil

with:

ovarystylestigma

Inside the ovary, there are one or more:

carpelsovules/seeds

In other flowers, there are:

multiple pistils

Draw and label what you see both looking down on theflower from above and in longitudinal section.

Now try flower diagnosis on other examples available inlab. Draw what you observe.

The Floral Formula

Inflorescences & Fruits

Family Identification

Identifying differences in the structure of the basic fourwhorls of a flower: calyx, corolla, androecium andgynoecium - often represented by a floral formula:

CaxCoxAxGx

is an important prerequisite to diagnosing angiospermfamilies. We'll look at each part in more detail here.

Calyx & Corolla:

Number of sepals and petals, designated by x in thefloral formula for Cax & Cox above, is an importantthing to know. Botanists typically count flower parts inthe following manner:

1, 2, 3, 4, 5, 6, 8, 10, many!

Count parts of the calyx and corolla if you can. In someflowers, it's difficult to distinguish sepals from petalssince both parts look essentially alike. For these, we usethe all-encompassing term tepal to describe allsepals/petals, and the whorls are counted together:

TxAxGx

Sometimes sepals of the calyx, or petals of the corolla,are fused together. If the fusion involves elements ofthe same whorl of parts, the sepals or petals aretermed connate. The connate condition is indicated inthe floral formula by drawing a circle around the countfor each connate whorl.

Androecium:

The whorl immediately above the petals is theandroecium. Each stamen usually consists offilament, and anther. The anther is usually comprisedof two connate pollen sacs (=microsporangia). Note

the structure of each stamen including the mode ofopening, termed dehiscence.

In many flowers, stamens are borne directly on thepetals. Fusion of flower parts like this, involving morethan one of the four whorls, is called adnation. Inbotanical lingo, we say "the stamens are adnate to thecorolla"! Check your flower out, count the number ofstamens and add this to your flower formula. If thestamens are adanate to the corolla, indicate this in yourfloral formula like this:

Cax Cox Ax Gx

Gynoecium:

The innermost whorl of the flower is the gynoecium.In all angiosperms, the ovule/seed is borne within anenclosing structure termed the carpel. In some flowers,the carpels are "free" from each other (i.e.,non-connate), and the flower is said to have multiplepistils. In most, however, two or more carpels arefused together to form a single pistil, comprised ofthe pollen receptive stigma, a short or elongate styleand ovary. An ovary, because it is comprised ofmultiple carpels, often has multiple cavities, termedlocules, in which are found the ovules. The presence ofone or more ovules per locule is an importantflower character, as well as the location of theattachment stalk of the ovule - funiculus - to the carpelplacenta. Dissect and diagnose the gynoecium of yourflower and add the number of carpels to your flowerformula.

Insertion:

Many flowers differ in insertion of the calyx, corolla,and androecium in relation to the ovary. Inhypogynous flowers, the ovary is termed superiorbecause it occurs above attachment of the other parts,and all four flower whorls insert (i.e, are attached)directly on the receptacle. In epigynous flowers, theother whorls insert instead on the top of the ovary itself.By definition, we term an ovary in this conditioninferior. In perigynous flowers, calyx, corolla andandroecium insert on a common floral cup or floraltube surrounding, but not adnate, with the ovary.Insertion of the floral cup or tube occurs below theovary on the receptacle, making the ovary superior.

Check your flower and determine its insertion pattern.Inferior ovaries are indicated in the floral formula byplacing Gx below the other symbols as if it were thedenominator of a fraction:

CaxCox AxGx

Now try your hand at analyzing other available flowers.

Depending on the size and weirdness of the flower, thisis often a challenging but highly entertaining exercise!

If a flower is small, use the dissection microscope toobserve each flower whorl. Draw each type of flower asa record of what you observe. Compare your flowerformula with others in the class to see if you reach thesame diagnosis.

The Flower

Inflorescences & Fruits

Family Identification

In angiosperms, flowers are often grouped together intoinflorescences. Recognizing different kinds ofinflorescences both in terms of how they develop as wellas how, sometimes, they function as a unit in attractingpollinators is useful basic knowledge about floweringplants.

The fruit is a structure that develops after fertilizationcomprised of one or more carpels with enclosed seeds.Often, the fruit serves as the unit of dispersal and, aswith the flower, intimate relationships between plantand different agents of dispersal have evolved overtime.

Just as in leaves and flowers, it is useful to have termsdescribing parts of an inflorescence. One importantthing to determine is whether an individual flower, oraggregate groups of flowers are pedicellate - that is,have a stalk or pedicel. Next, one needs to determinethe order of maturation of flowers within theinflorescence. Let's call the first flowers of aninflorescence to open (and set fruit) the "oldest".There are two orders of maturation:

centrifugal - the oldest flowers at the tip (or center) ofthe inflorescence with progressively younger flowersproximally (or toward the outside).

centripetal - the oldest flowers at the base (orperiphery) of the inflorescence with progressivelyyounger flowers distally (or toward the middle).

As directed by your TA, observe the available examples

of inflorescences. Identify the inflorecence type basedon your text and the following key:

Centripetal Inflorescences

flowers pedicellateinflorescence compound - panicleinflorescence simple - raceme

flowers not pedicellate - spike

Centrifugal Inflorescences

flowers distinctly pedicellatepedicels worled - umbelpedicels alternate or opposite

inflorescence flat-topped - corymbinflorescence not flat-topped - cyme

flowers not pedicellate, discoid - head

In addition, there are catkins - elongate clusters ofhighly reduced flowers usually missing eithergynoecium or androecium and involved in windpollination.

Different types of fruits in angiosperms are also usefulin identification, and provide insight into differentpatterns of evolution within the group. As directed byyour TA, find the definitions of the following termsusing descriptions in your text:

simple vs aggregate vs multiple fruitsfleshy vs dry fruitsdehesicient vs indehiscent fruits

Identify the fruit type using the following simplifiedkey:

simple dry fruits

indehiscentnot winged - achenewinged - samara

dehiscentsingle carpel

dehiscent along one suture - follicledehiscent along two sutures - legume

multiple carpelsmultiple seeds- capsuleone or two seeds - nut

simple fleshy fruits

fleshy endocarp - berrystony endocarp - drupe

compound fruits

from single flower - aggregate fruitfrom inflorescence - multiple fruit

Please be aware that there are many more types offruits than is represented by the key above. However,knowing these common types is a good place to start!

The Flower

The Floral Formula

Family Identification

Angiosperms are a highly diverse group. It has beenrecognized for a long time that the best way to identifyindividual species is to first concentrate at the level offamily. There are around 400 families of floweringplants worldwide with exact number depending on howexperts "lump" or "split" them. Within a particulararea such as the Eastern Hardwood forest, the numberof families is often considerably less. This means thatwith careful observation and a little practice, it isusually possible to recognize most of the common oneson sight. Following this, it becomes possible to narrowthings down first to genus and then, if necessary, toindividual species, varieties, cultivars, and so forth. Thisis the value of the Linnean hierarchy as a practicaltool!

Since the days of Linneaus, recognition of most if not allangiosperm families can be made using flower form assummarized, in part, by the floral formula. For somefamilies, such as cacti, palms or sunflowers, vegetativefeatures or form of inflorescence are also very useful.The best strategy of identification overall is to collectand summarize as many distinctive feastures of a plantas one can because, for a particular family, you mightbe surprised what may turn out to be relevant.

A useful means of summarizing information about aplant is through the time-honored tradition ofproviding a diagnosis. In Botany, a diagnosis is aformal list of nouns identifying the part beingdescribed such as androecium or gynoecium. After the

T

noun, one then uses one, or more often several,adjectives to describe the unique features observed ofthis plant compared with all others. The uniquefeatures (adjectives) are termed the plant's character(or state) for each part (noun). In naming a newspecies, the International Code of BotanicalNomenclature requires along with properdocumentation, a researcher must provide a diagnosisof this type. For living plants, the code further stillrequires that the formal diagnosis and the official namemust be in Latin - the international language of plantsystematics.

To see the International Code of Nomenclature for

algae fungi & plants (ICN) online click here:

Obtain a specimen of available material. Draw andlabel all the parts you see.

Be sure to observe all parts of the plant availableincluding both vegetative regions and fertileinflorescence containig one or more flowers.

Construct a diagnosis of what you can see. Each lineoshould consist only of a single noun describing eachplant part followed by one or more adjectivesdescribing states. Feel free to subdivide diagnosis aplant part (noun) into a series of more specificsubcategories. For instance, you may wish to say on oneline something like this:

flower, red.

However, will no doubt also want further subdivide"flower" into:

flower, red.flower-calyx, 5-merous (i.e., with 5 sepals).flower-corolla, connate.flower-androecium, adnate to corolla.

and so forth. Note that further subdivision is alwayspossible and often desired, e.g.:

flower-gynoecium, connate, 5-merous.flower-gynoecium-stigma, sessile.

Don't forget vegetative characters such as:

shoot, ascendent, green.shoot-insertion, opposite-decussateleaf, simple, entire, serrulate, pubescent.

One written, it's time to put your diagnosis to use! Findthe following website:

Worldwide flowering plant family identification

This lovely web implementation from professor Phillipsat Colby College is an example of a polyclave key. Youenter all the information you can from your diagnosisby checking appropriate boxes.

Note that terminology often varies from one botanist tothe next, so it may be necessary to consult the extensiveand well-written glossary in your textbook forunfamiliar terms. This happens a lot even with seasonedbotanists!

Once all your diagnostic information is entered, click"Submit Form". The key will then give you a potentiallist of families. Each family has at least one memberwith the diagnostic features you entered. Of course, themore characters you enter, the smaller the list becomes.

From this, search the web for each candidate family foryour plant. In authoritative websites, your are verylikely to encounter a synoptic description of thefamily. Its form will be very familiar! Take a look at thisdescription and other information such as conspicuousgenera and, of course, pictures. From this, you canprobably narrow things down to a single family. Thepolyclave key provides multiple hints for whatadditional features and states to look for in your plantthat may originally have been overlooked. Onceobserved and entered, the key will narrow things downalso.

The Flower

The Floral Formula

Inflorescences & Fruits