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Welcome to Northwest Plants
Northwest Indian
College
ENVS 201 Spring Quarter 2012
Plant Parts
vegetative
organs:
reproductive
components:
stems
flowers
roots
fruits
leaves
seeds
Today:
Stems
Stem Features &
Functions
above ground axis of vascular plants, as well
as anatomically similar below ground
portions (e.g., rhizomes, bulbs & corms)
trunks & branches are stems
may be photosynthetic (e.g., cacti)
may store food (in some species)
etc.
Stem Regions & Other
Features
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 bud
bud scale & bud scale scar
epidermis, bark
lenticels (in some species, also in some
roots, fruits, etc.)
leafy branch (silver maple), showing nodes,
internodes and buds)
apical (terminal) bud
silver maple with buds
lateral buds
flower buds (silver maple)
stems of silver maple with bud scales, bud scale
scars, bark & lenticels
Stem Features
Associated with
Leaves
leaf scar (site of leaf abscission)
vascular bundle scar
stipular spine (in some species, e.g., black
locust)
silver maple leaf scar and vascular bundle scars
black locust stipular spines
Stem Modifications
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)
stolon (Fragaria, strawberry)
rhizome (Polypodium, fern)
tuber (Solanum, potato)
corm (Gladiolus)
Stem Modifications
(continued)
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)
bulb (Allium, onion)
cladophyll (Opuntia, prickly pear)
tendril (Vitis, grape)
thorn (Gleditsia, honey locust)
prickle (Rubus)
Ginkgo
spur branch or shoot
Betula (birch)
Stem Anatomy—Lateral
Meristems
vascular cambium - thin region of cells that
give rise to (secondary) xylem, (secondary
phloem) and parenchyma
cork cambium (phellogen) - thin region of
cells that give rise to phellum (cork)
outwardly and phelloderm inwardly
cambial zone—>
vascular cambium (Tilia)
<—cambial region
cork cambium (Tilia)
Stem Anatomy—
Tissues
xylem (wood) - main water- & mineraltransporting 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—
Cultural
Considerations
“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 (3-year-old, Tilia)
Questions &
Comments?
Stems are cool.
Hy’shqe!