ENVS 201 Spring Quarter 2012

Northwest Indian College

Welcome to Northwest Plants

Plant Parts

stems

roots

leaves

flowers

fruits

seeds

vegetative organs:

reproductive components:

Today:Stems

above ground axis of vascular plants, as well as anatomically similar below ground portions (e.g., rhizomes, bulbs & corms)trunks & branches are stemsmay be photosynthetic (e.g., cacti)may store food (in some species)etc.

Stem Features & Functions

node (region where leaves may be borne)internode (region between nodes)apical (or terminal) bud (at tip of stem)axillary (or lateral) bud (in axil, on side of stem)flower budbud scale & bud scale scarepidermis, barklenticels (in some species, also in some roots, fruits, etc.)

Stem Regions & Other Features

leafy branch (silver maple), showing nodes, internodes and buds)

silver maple with buds

apical (terminal) bud

lateral buds

flower buds (silver maple)

stems of silver maple with bud scales, bud scale scars, bark & lenticels

leaf scar (site of leaf abscission)vascular bundle scarstipular spine (in some species, e.g., black locust)

Stem Features Associated with

Leaves

silver maple leaf scar and vascular bundle scars

black locust stipular spines

stolon (runner) - aerial, horizontal, often root at nodes (e.g., strawberry)rhizome - +/- horizontal, underground (e.g., bamboo, irises, ferns)tuber - end of underground stem, fleshy, food storage (e.g., potato)corm - shortened, usu. below ground, enclosed by dry scalelike leaves (e.g., gladiolus)

Stem Modifications

stolon (Fragaria, strawberry)

rhizome (Polypodium, fern)

tuber (Solanum, potato)

corm (Gladiolus)

bulb - short, underground stem with fleshy leaf bases (e.g., onion)cladophyll (also: cladode, phylloclad) - leaflike stem (e.g., cactus)tendril - long, slender, coiling stem (e.g., grape) in climbing plants (or a leaf or other structure in other species)thorn - hard, sharp-pointed, modified branch (e.g., honey locust)prickle - sharp-pointed superficial outgrowth (e.g., Rubus)spur (spur branch/shoot, or short shoot) - short stem on a branch with very short internodes (e.g., ginkgo)

Stem Modifications (continued)

bulb (Allium, onion)

cladophyll (Opuntia, prickly pear)

tendril (Vitis, grape)

thorn (Gleditsia, honey locust)

prickle (Rubus)

spur branch or shoot

Ginkgo

Betula (birch)

vascular cambium - thin region of cells that give rise to (secondary) xylem, (secondary phloem) and parenchymacork cambium (phellogen) - thin region of cells that give rise to phellum (cork) outwardly and phelloderm inwardly

Stem Anatomy—Lateral Meristems

vascular cambium (Tilia)

cambial zone—>

cork cambium (Tilia)

<—cambial region

xylem (wood) - main water- & mineral-transporting tissue (in vascular plants)phloem - main food-conducting tissue (in vascular plants)periderm (bark) everything outside vascular cambium: phelloderm, phellogen & phellum (bark sometimes said to also include secondary phloem)

Stem Anatomy—Tissues

“sap” - edible region from vascular cambium outward, including cambial cells, phloem and possibly some phelloderm (inner layer of the bark); mainly the softest parts (e.g., of cottonwood)“inner bark” - region possibly as described above (e.g., of red cedar)

Stem Anatomy—Cultural

Considerations

stem (3-year-old, Tilia)

Questions & Comments?

Stemsarecool.

Hy’shqe!