Plant Morphology

Stem components

internode, node

internode

region of stem between nodes

node

solid joint of a grass stem

Types of stems

upright, stolon, rhizome

tiller (Grass)

upright, ascending stem

Stolon (Grass)

creeping, aboveground stem (runners)

Stolons can produce what at each node? (Grass)

new shoots and roots

Rhizome (Grass)

horizontal, underground stem

sheath (Grass)

surrounds grass stem above the node

collar region (Grass)

area of junction between blade and sheath

blade (Grass)

portion of leaf connected to the sheath

ligule (Grass)

occurs where sheath and blade join

ligule morphologies (Grass)

membrane, fringe of hairs, hardened ring

auricle (Grass)

outgrowths from base of blade that encircle the stem if prominent

auricles may be

small or absent

Inflorescences (Grass)

spike

Spike

spikelets are attached directly to central axis, no branching

Raceme

spikelets occur on single branch attached to central axis

Panicle

spikelets occur on multiple branched inflorescences

All inflorescences have

spikelets

Spike inflorescence example

wheat

Raceme inflorescence example

bahiagrass (typewriter weed)

Panicle inflorescence example

oat

Meristem

regions of actively growing, undifferentiated cells

apical meristem

at tip or stem of root

intercalary meristem (Grass)

occur at base of internode, can give rise to new shoots

(Grass) Meristems enable

formation of nodes and internodes

How does meristem growth lead to elongation? (Grass)

Cells in internode region expand and grow, elongating the plant

(Grass) Buds are found

at the base of internodes; produce new shoots

(Grass) Apical meristems also produce

new cells that will become the stem

(Grass) Stem nodes are

closely stacked with very short internodes

Legumes

clover, vetches, alfalfa, birdsfoot trefoil

Crown (legume)

underground basal portion of stem; overwintering structure in cold climates

Petiole (legume)

leaf stalk

Leaflet (legume)

one of the “blades” of a compound leaf

Petiolule

stalk of a leaflet

Stipules (legume)

leaflike outgrowths at the base of the petiole

Legume inflorescences

raceme, head

Structures at end of racemes in legumes

floret

Head inflorescence morphology (legume) ex.

clover

Alfalfa root morphology

thick, fleshy taproots

Ryegrass root morphology

fibrous (diffuse) root system

How are perennial peanut rhizomes effective to the plant?

grazing and haying tolerant due to nutrient storage; bud sites provide new growth

bermudagrass rhizomes

nodes underground give rise to new shoots and roots

bahiagrass rhizomes

very close to soil surface; striations (nodes) produce new shoots and roots

Why are rhizomes important in N Florida?

improve cold tolerance of plants