Chapter 22 Plant Diversity 22 1 Introduction to

Chapter 22 Plant Diversity

22 -1 Introduction to Plants 1. What is a plant? 1. Multicellular 2. Eukaryotes 3. Cell walls made of cellulose 4. Carry out photosynthesis using chlorophyll a and b 5. Develop from multicellular embryos 1. Can think of them like stationary animals that eat sunlight!!

The Plant Life Cycle: Alternation of Generations 1. Gametophyte = haploid (N), gameteproducing plant 2. Sporophyte = diploid (2 N), sporeproducing plant 3. Gametes are produced by meiosis; spores are produced by mitosis

Plant Reproduction 1. Alternation of Generations 2. 2 stages 1. Gametophyte Stage—haploid (n) 1. makes gametes 2. gametes join to start sporophyte 2. Sporophyte Stage—diploid (2 n) 1. produces spores which grow into gametophyte 2. undergoes meiosis

1. What Plants Need to Survive 1. Sunlight—to carry out photosynthesis 1. leaves are adapted to be broad and flat for maximum absorption 2. Water and Minerals—for photosynthesis too! 1. lose water through transpiration through stomata in leaves; evolved a waxy cuticle to minimize water loss 3. Gas Exchange—CO 2 and O 2 4. Movement of Water and Nutrients 1. take up water through roots, has specialized tissues to help move it through the entire plant 1. xylem- moves water and nutrients upward 2. phloem- moves sugar down toward roots

1. Early Plants 1. In Water 2. First plants evolved from something like our multicellular green algae 3. dependent on water for reproduction; no vascular tissue (xylem and phloem) so plants needed to be close to ground; 4. was moss-like and evolved slightly to resist water loss

Vascular Tissue 1. A transport system in plants specialized to conduct water and nutrients throughout the plant 2. Allowed plants to grow, reach new heights 3. 2 types of vascular tissue: xylem & phloem 1. 2. Xylem: carries water upward Phloem: carries nutrients (food) 4. For millions of years, plants didn't grow larger, but 420 mil. yrs ago, vascular tissue appeared

1. The first plants on land were trailblazers! 1. had to learn to acquire, transport, and conserve water 2. Without plants, we humans/animals could not be here! 2. Evolved other characteristics such as flowers to attract insects, seeds , roots, stems, leaves.

Kingdom Plantae Divided by: Waterconducting tissue, seeds, and flowers 1. 1. mosses/bryophytes (nonvascular) 2. 2. seedless vascular plants 3. 3. Gymnosperms 4. 4. Angiosperms (flowering plants) 235, 000 species (90% of all living plants)

Flowering plants Cone-bearing plants Ferns and their relatives Flowers; Seeds Enclosed in Fruit Mosses and their relatives Seeds Water-Conducting (Vascular) Tissue Green algae ancestor

22 -2 Bryophytes 1. Mosses and their relatives are BRYOPHYTES- nonvascular plants 2. Grow in moist, shaded areas!! 3. Depend on water for reproduction, lack vascular tissue 4. Land adaptations: grow in very moist environments; draw up water by osmosis; very low to the ground

1. Groups of Bryophytes 2. Mosses (Bryophyta) 1. Found in swamps, bogs, near streams, rainforests, POLAR regions! 2. Have rhizoids- long, thin cells strung out to absorb water and nutrients- pg. 557

1. Liverworts (Hepaticophyta) 1. Liver-shaped, need damp soil year-round 2. Gametophytes— broad and thin—use soil for moisture 3. produce “umbrellas” asexually 4. Gemmae— multicellular spheres that have many haploid cells

1. Hornworts (Anthocerophyta) 1. Need damp soil year-round 2. Gametophytes- same type as liverworts 3. Sporophytes- looks like a tiny, green horn

1. Life Cycle of Bryophytes 1. GAMETOPHYTE stage is dominant and carries out most of photosynthesis 2. Fertilization in these plants requires the sperm to swim- need water! 3. Protonema—a young mass of filaments produced by a spore 4. Sperm: antheridia 5. Egg: archegonia these can be on the same or different plants

1. Human Uses 1. Sphagnum- giant sponge 2. Peat- burned as fuel 3. Peat moss- holds water in garden soil, increases acidity of soil

22 -3 Seedless Vascular Plants 1. Evolution of Vascular Tissue Specialized to conduct water and nutrients. 2. Tracheids- hollow cells with thick cell walls that resist pressure. 1. Connected end to end 2. Allow water to move through a plant more efficiently than by diffusion alone. 3. Tracheids are the key cells in xylem 1. Carries water upward from roots to every part of plant 1.

1. Phloem Second type of vascular tissue. 2. Transports solutions of nutrients and carbs. 3. Main cells are long and specialized. 1. 2. Both xylem and phloem can move fluids against gravity. 3. Also evolved lignin, substance that makes cells walls rigid. 1. Allow plants to grow upright and reach great heights.

1. Ferns and Their Relatives 1. 3 groups of seedless vascular plants: 2. Club mosses 3. Horsetails 4. Ferns 1. True vascular tissues 2. Underground stems (rhizomes) 3. Large leaves (fronds)

Plant Vocabulary Roots - underground organs that absorb water and minerals Leaves -photosynthetic organs that contain one or more bundles of vascular tissue Vein - cluster of vascular tissue in leaves (xylem and phloem) Stems - supporting structures that connect roots & leaves, carrying water & nutrients between them

Club Mosses 1. Today, club mosses are small plants that live in moist wetlands 2. Fossilized club mosses form today's coal

Ferns: Most Numerous Type of Seedless Vascular Plant 1. More than 11, 000 species today 2. Ferns reproduce by producing spores! 3. Fronds = large leaves 4. Rhizome = underground stems

Life Cycle of Ferns

Fern Reproduction (By Spores!) Ferns and other vascular plants have a life cycle in which the diploid sporophyte is the dominant stage. The sporophyte produces spores by meiosis! sporangia - containers on fronds holding spores sori - clusters of sporangia When spores germinate, they turn into haploid gametophytes. The small gametophyte grows rhizoids (long rootlike cells) and becomes the mature gametophyte. It produces sperm and egg cells, which unite in fertilization to produce a sporophyte embryo, which grows into the mature sporophyte fern.

22 -4 Seed Plants 1. Can be divided into two groups: 2. Gymnosperms 1. Conifers (pines and spruces), cycads, ginkgoes, gnetophytes 3. Angiosperms 1. Grasses, flowering trees and shrubs, wildflowers, cultivated flowers.

1. Reproduction Free From Water 1. Adaptations allow seed plants to reproduce without standing water 1. Flowers or cones 2. Transfer of sperm by pollination 3. protection of embryos in seeds 2. Seed plants do not require water for fertilization of gametes 1. so seed plants can live almost anywhere!

1. Cones and Flowers 1. Cones- seed-bearing structures of gymnosperms 2. Flowers- seed-bearing structures of angiosperms 3. gametophyte structure lives inside cone/flower! 2. Pollen grain 1. Contains male gametophyte 2. Spern is carried by wind, insects, birds, small animals, or bats 3. Pollination is the transfer of pollen from the male reproductive structure to the female structure.

Seeds 1. Embryo in a protective covering (seed coat), surrounded by a food supply. 2. Embryo = organism in its early stage of development 3. seed coat = structure that surrounds and protects plant embryo and prevents it from drying out

1. Evolution of Seed Plants After Carboniferous and Devonian, Earth became drier, many mosses and ferns died out. 2. Replaced by seed plants that could deal with drier conditions (fossils from 360 mil. yrs ago) 1.

1. Gymnosperms- Cone Bearers 1. 2. 3. 4. “naked seeds” Gnetophytes Cycads Ginkgoes

1. Conifers 1. 2. Most common gymnosperms P. Coniferophyta- pines, spruces, firs, cedars, sequoias, redwoods, and yews. 2. Ecology of Conifers Wide variety of habitats: mountains, sandy soil, and cool, moist areas. 2. Adaptations 1. Long, thin leaves, reduces surface area 2. Thick, waxy layer 3. Openings for gas exchange located below surface of leaf in cavity 4. Most are “evergreens”

The Pine Cone

Temperate rain forest outside Seattle, WA

22 -5 Angiosperms- Flowering Plants 1. Flowers and Fruits 1. Flowers are reproductive organs- attract animals which transport pollen, more efficient than wind pollination. 1. Flowers contain ovaries: surround and protect seed 2. Fruit is the thick tissue wall surrounding the seed, animals transport to distant locations via the digestive system.

1. Diversity of Angiosperms 1. Monocots and Dicots 1. Named for the number of seed leaves (cotyledons) in plant embryo. 2. Mono- one 3. Di- two

1. Woody and Herbaceous Plants 1. Woody plants- thick cell walls that support the plant body. 1. Trees, shrubs, some vines (ex. Roses) 2. Herbaceous- stems are smooth and nonwoody. 1. Dandelions, sunflowers, etc.

1. Annuals, Biennials, Perennials 1. Annual - completes a life cycle in one growing season 2. Biennial - completes life cycle in two years 1. 1 st year: germinate and grow roots, very short stems, sometimes leaves. 2. 2 nd year: grow new stems and leaves, then flowers and seeds. 3. Perennial - lives for more than two years.