Chapter 34 Plant Form and Function Biological Science

root system

anchors the plant and takes in water and nutrients; belowground portion of plant; absorptive regions are tubelike; contain a central taproot and numerous lateral roots

shoot system

harvests light and CO2; aboveground portion of plant body; absorptive regions are flat

node

where leaves attach

stem

vertical aboverground plant structure

internodes

segments between nodes

leaf

photosynthetic organ appendage

axillary bud

from above leaf attachment to node that may grow into a branch

apical bud

tip of stem and branch that could grow into a flower or a reproductive structure

stolons

horizontal stems that produce adventitious roots

rhizomes

horizontal stem that produces new plants at nodes (asexual production)

tubers

underground rhizomes; eyes of potatoes

simple leaf

blade + petiole

compound leaf

blades divided into leaflets

surface are to volume ratio

absorption happens across surface but takes up space

epidermis

dermal tissue that makes up a plant's outer covering; contains the cuticle and trichomes

cuticle

wax coating that defends the plant from water loss and pathogens

stomata

Small openings on the underside of a leaf through which carbon can be assimilated and water is lost as water vapor

trichomes

Tiny, spikelike projections on some leaves for protection

ground tissue system

synthesis and storage of pigments, hormones, and toxins for defense

totipotent

Stem cells with the potential to differentiate into any type of cell.

parenchyma

simple tissue that are filled with chloroplasts and have thin cell walls; site of photosynthesis; totipotent; ground tissue system

collenchyma

thick cell walls with simple tissue; underneath the epidermis of stems; stretch, allowing flexibility in wind; strings of celery; ground tissue system

sclerenchyma

thick, primary and secondary cell walls; dead at maturity and only used for rigidity; fibers and used for protection

vascular tissue system

structure responsible for long distance transport of water and nutrients in plants; contains xylem and phloem

xylem

conducts water and nutrients from root to shoot functioning like pipelines and provides structural support; composed of water conducting cells and parenchyma cells and fibers

tracheids

A water-conducting and supportive element of xylem composed of long, thin cells with tapered ends and walls hardened with lignin

pits

areas where only primary cell wall is present in tracheids

vessel elements

located in xylem; conduct water better than tracheids bc of width and perforations

perforations

openings in cell walls at ends of vessel elements

Phloem

conducts sugar in both directions of plant; contains sieve-tube elements and companion cells

sieve-tube elements

long thin cells with perforated ends called sieve plates that transport sugars and nutrients; lack cell organelles

companion cells

maintain cytoplasm and membrane of sieve-tube elements; support their metabolic activity

meristem

population of undifferentiated cells with the ability to undergo mitosis

apical meristem

tip of each root and shoot that extend the body outward; primary growth

protoderm

The outermost primary meristem, which gives rise to the epidermis of roots and shoots; dermal tissue system

procambium

A primary meristem of roots and shoots that forms the vascular tissue.

ground meristem

primary meristem that gives rise to the ground tissue system (bulk of body)

root cap

a structure that covers the tip of a root, protecting the apical meristem from injury

zone of cellular division

contains the apical meristem and primary meristems; where cell division occurs

zone of cellular elongation

cells that increase length

zone of cellular maturation

older cells complete differentiation into dermal, vascular, and ground tissues; most important for absorption - epidermal cells produce root hairs

root hairs

tiny hair-like extensions that increase the surface area of the root allowing it to absorbs more water and nutrients

vascular bundles

groups of vascular tissue surrounded by ground tissue - pith and cortex

pith

ground tissue towards the center of the stem

cortex

ground tissue between vascular bundles and epidermis

secondary growth

increases width of roots and shoots; increases amount of conducting tissue and provides structural support for growth

cambium

cylinder that runs length of root, trunk, or branch made up of meristem cells

vascular cambium

cylinder of meristematic cells located between the secondary xylem and secondary phloem in roots, trunks, and branches; interior width growth

cork cambium

meristematic cells beneath epidermis located near outer perimeter of roots, trunks, and branches; exterior width growth of cork cells; bark of tree made of lignin

secondary phloem

inside of bark

secondary xylem

wood; composed of dead xylem cells with lignin in walls; only for structure, not transport

dormancy

vascular cambium stops growing for a portion of the year (winter)

Monocot

angiosperm whose seeds have one cotyledon

eudicot

True dicot; one of the flowering plants generally characterized by embryos with two cotyledons.

cotyledon

first leaf or first pair of leaves produced by the embryo of a seed plant