BIO151 PLANT STRUCTURE & FUNCTION

monocots

develop a mass of small, fibrous roots

dicots

have a taproot (singe large root) with some small lateral branches

adventitious roots

develop from nodes of aboveground stem or from leaves

node

site of leaf or branching shoot production

internode

portion of stem between nodes

apical bud

site of elongation at tip of shoot

axillary bud

bud at node

rhizome

underground stem

stolon

aboveground horizontal stem

bulb

underground stem w. modified leaves (stores nutrients)

corm

like a bulb, but nutrients stored in stem tissue (meristem)

tuber

thickened rhizome or stolon

types of dermal tissue

cuticle, stomata, guard cell

cuticle

waxy covering of epidermis, prevents water loss

stomata

volume controlled by active transport & osmosis

guard cell

open & close stomata to allow leaf interior to exchange gas to air

meristem

undifferentiated tissue, containing cells that can divide leading to cells that elongate & become differentiated

trichomes

outgrowths (a type of epidermal cell), think of the needles on cacti

periderm

replaces the epidermis in older regions of stems and roots

types of vascular tissue

xylem & phloem

xylem

conducts water & dissolved minerals upward from roots into the shoots, the cells are mostly dead at maturity

phloem

transports sugars, products of photosynthesis, from where they are made to where they are needed or stored (usually roots & sites of growth such as leaves & fruits)

stele

vascular tissue of a root or stem collectively

types of ground tissue

pith & cortex

pith

internal to the vascular tissue

cortex

external to the vascular tissue

phloem (sieve tube elements)

lost almost all organelles, sugar-rich phloem sap flows through unobstructed cytoplasm, connected to companion cells

phloem (companion cells)

retains organelles, supports sieve tube elements, helps load with sugars

differentiated types of ground tissue

parenchyma, collenchyma, sclerenchyma

parenchyma

relatively soft primary cell walls

collenchyma

irregularly thickened primary cell walls (cellulose)

sclerenchyma

cell with lignified secondary cell walls, dead at maturity

annual

plant lives for a year, dies after producing seeds & fruits

biennial

plant lives for two years, flowers & fruits only in second year

perennials

lives for many years, has a growth cycle of blooming, seeding, fruiting, etc..

indeterminate

continues extending a shoot as long as environmental factors are favorable

determinate

forms organs or structures with distinct shapes

meristems (apical)

tips of shoots & roots; elongation of structures (primary growth)

meristems (lateral - woody dicots)

around circumference of stem; expands circumference (secondary growth) by adding additional vascular tissue