PLANT DIVERSITYChapter 22

Introduction to Plants Multicellular Eukaryotes Cell walls

Cellulose Develop from

Embryos Photosynthetic

Chlorophyll a & b

What Plants Need… Sunlight Water Minerals Gas exchange And movement

of water and nutrients throughout the plant body

Bryophytes Depend on

water for reproduction

Lack vascular tissue Must draw water

by osmosis Thus are very

low to the ground

Mosses, liverworts, hornworts

Seedless Vascular Plants Contain vascular

tissue that transports materials throughout the plant against gravity Xylem- carries

water Phloem- carries

nutrients Club mosses,

horsetails, ferns

Seed Plants Adaptations allow

these plants to reproduce in areas without water

Flowers, cones, pollen, and seeds

Gymnosperms bear seeds directly on surface of cones

Angiosperms Developed

unique reproductive organs called flowers

Flowers contain ovaries which surround and protect seeds

Diversity of Angiosperms Monocots- one cotyledon (seed leaf) Dicots- two cotyledons

Diversity of Angiosperms Woody Plants-

made of thick cell walls that support the plant Trees, shrubs,

vines Herbaceous

Plants- do not produce wood as they grow Dandelions,

sunflowers

Angiosperm Life Spans Annuals- grow, flower,

produce seeds and die in one season Petunias, pansies, zinnias

Biennials- germinate and grow slightly in the first year; produce flowers and seeds in the second and then die Foxglove, parsley, celery

Perennials- live many years; may die back in winter but replace itself in the spring Maples, honeysuckle, grasses

ROOTS, STEMS & LEAVESChapter 23

Specialized Tissues in Plants Roots

Absorb water and dissolved nutrients

Anchor plants to the ground

Stems Support the plant

body Carries nutrients up

the plant Leaves

Contain the photosynthetic systems

Plant Tissue Systems Dermal Tissue- “skin”

Protects against water loss May give added surface area

Vascular Tissue Xylem- tracheids & vessel

elements Phloem- sieve tube elements &

companion cells Ground Tissue

Parenchyma- storage & support

Collenchyma and Schlerenchyma function in support

Plant Growth Meristematic

Tissue- produces new cells by mitosis Primary growth

New cells at the tip of the stem or root are undifferentiated Apical meristem

Gradually as the cell matures, it differentiates.

Roots Taproots- dicots Fibrous Roots-

monocots Mature roots have

an epidermal layer and a central cylinder of vascular tissue separated by ground tissue called a cortex

Can you guess what root hairs are for?

Stems Produce leaves,

branches, & flowers

Hold leaves up in the sunlight

Transport nutrients

Primary growth- length

Secondary growth- width Wood

Leaves Optimized for absorbing light & photosynthesis Blades collect sunlight and are attached to the

stem by a thin stalk called a petiole. Compound leaves are divided into many

separate leaflets.

Leaf Functions Transpiration- loss

of water through the leaves

Plants keep stomata open just enough to allow photosynthesis to take place but not so much that they lose too much water

Transport in Plants The combination of

root pressure, capillary action, & transpiration provides enough force to move water through the xylem of even the tallest plants.

Capillary action results from a force called adhesion

Xylem and Phloem Transport

REPRODUCTION IN SEED PLANTS

Chapter 24

Reproduction with Cones & Flowers Gymnosperms-

cones produced by mature sporophyte plant

Pollen cones- male

Seed cones- female

Structure of Flowers

Stamens- male Anther &

filament Carpels-

female Pistil- ovary,

style, stigma

Composed of specialized leaves Sepals- outer part of flower Petals- often brightly colored

Life Cycle of Seed Plants Reproduction

takes place in the flower

After pollination and fertilization, seeds develop in structures fruits

Most gymnosperms are wind pollinated.

Most angiosperms are pollinated by animals.

Seed dispersal

Animals- eat the fruit and pass the seeds

Wind and water- float

Seed Dormancy Factors such as temperature and moisture

can cause seeds to end dormancy and germinate

Plant Propogation Vegetative

reproduction- produce plants from horizontal stems, plantlets, and roots.

Cuttings, grafting, or budding can also be used in agriculture.

PLANT RESPONSES & ADAPTATIONS

Chapter 25

Plant Hormones Control growth and development, & a plant’s responses Auxins- produced in apical meristem; stimulate cell elongation Cytokinins stimulate cell division/growth; cause seeds to sprout Gibberellins produce dramatic increase in size of stems & fruits Ethylene stimulates fruits to ripen

Plant Responses Gravitropism-

(auxin) Roots grow

downward Phototropism-

(auxin) Stems grow to light

Thigmotropism- touch

Photoperiodism- causes timing flowering & growth

Winter Dormancy- growth &photosynthetic activity decreases

Plant Adaptations Many aquatic plants

have tissues with large air spaces to allow in oxygen

Salt-tolerant plants have special cells to pump out excess salts

Xerophytes “dry plants”- desert plants with extenive roots, reduced leaves, and thick stems

Nutritional Specialists Live in environments

with low levels of nutrients in the soil

Carnivorous plants- lack N-fixing bacteria due to acidic/wet conditions

Parasitic plants- lack chlorophyll and must extract nutrients and water from host plants

Epiphytes Grow on other

plants Not rooted in soil BUT ARE NOT

PARASITES! Most found in

tropical rainforests

They gather their own moisture and produce their own food

Chemical Defenses Protect against

insect and animal attack

Some are poisonous

Some imitate hormones that prevent insects from reproducing

Aspirin, codeine, & nicotine are derived from plants