copyright © 2009 pearson education, inc. plant structure and function

Copyright © 2009 Pearson Education, Inc.

PLANT STRUCTURE AND FUNCTION

Evolution and types of plants

Since the earth was once covered in water, plants had to make three adaptations to survive on land

The ability to prevent water loss

The ability to reproduce in the absence of water

The ability to absorb and transport nutrients

Plants can be placed under two groups

Vascular- having true roots, leaves, and stems

Ex. ferns, conifers, flowering plants

Nonvascular- not having true roots, leaves, and stems

Ex. mosses, liverworts, hornworts

Vascular Plants can be divided into two groups

Seedless Plants Made up of ferns and

plants closely associated with ferns

Seed Plants Two types of seed

plants

Gymnosperms- which includes pine trees, produce seeds that are not encased in fruit

Angiosperms- aka flowering plants, produce seeds within a protective fruit

Monocots

– One cotyledon

– Parallel leaf venation

– Scattered vascular bundles

– Flower parts in 3s or multiples of 3

– Fibrous roots

The two main groups of angiosperms are the monocots and the dicots

Dicots- aka eudicots

– Two cotyledons

– Branched leaf venation

– Ring of vascular bundles

– Flower parts in 4s or 5s (or multiples)

– Taproot system

The two main groups of angiosperms are the monocots and the eudicots


A typical plant body contains three basic organs: roots, stems, and leaves

Plants absorb water and minerals from soil through roots

Plants absorb the sun’s energy and carbon dioxide from the air through shoots (stems and leaves)

Plant roots depend on shoots for carbohydrates produced via photosynthesis

Plant shoots depend on roots for water and minerals


Plant roots– Anchor plant

– Absorb water and nutrients

– Store food

Plant shoots– Stems, leaves, and

reproductive structures

– Stems provide support

– Leaves carry out photosynthesis

A typical plant body contains three basic organs: roots, stems, and leaves

RoothairRoot

hairs

Terminal bud

Flower

Node

Internode

Epidermal cell

Taproot

Stem

Axillary budPetiole

BladeLeaf

Rootsystem

Shootsystem


Many plants have modified roots, stems, and leaves

Modifications of plant parts are adaptations for various functions

– Food or water storage

– Asexual reproduction

– Protection

– Climbing

– Photosynthesis

Root modifications

– Food storage

– Examples include carrots & potatoes


Stem modifications

– Runners (allow for asexual reproduction)


Leaf modifications

– Climbing

– tendril

– Example: pea plants

– Protection

– Thorns or spines

– Example: Cactus spine


Plant cells and tissues are diverse in structure and function

Plants cells have three structures that distinguish them from animals cells

– Chloroplasts used in photosynthesis

– A large, fluid-filled vacuole

– A cell wall composed

of cellulose


PLANT GROWTH


Primary growth

Plants are categorized based on how long they live

– Annuals complete their life cycle in one year

– Biennials complete their life cycle in two years

– Perennials live for many years

Axillary buds

Terminal bud

Arrows =directionof growth

Roottips

Primary growth allows roots to push downward through the soil and shoots to grow upward

Secondary growth increases the girth of woody plants

Year 1Early Spring Year 1

Late Summer

Year 2Late Summer



Cork cambium produces the outer bark


Wood annual rings show when new growth starts each year.

Sapwood (transport)- functional, lighter-colored wood near the outside of the trunk

Heartwood (storage)- the darker wood at the center of the trunk


Xylem- transports water

Phloem- transports food

copyright © 2009 pearson education, inc. plant structure and function

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