Evolution and Diversity of Plants Chapter 24

Evolution Modern day plants evolved from freshwater green algal species Evidence both contain chlorophyll a and b store excess energy as starch have cellulose cell walls Stone warts are the closest DNA relative

Evolution had 4 major events 1-Nonvascular plants have multicellular embryos that are protected and nourished within structures that produce eggs 2- Seedless vascular plants- Vascular tissue conducts water and organic nutrients within its roots, stems, and leaves Approx- 430 million years ago

Evolution had 4 major events 3- Gymnosperms- Seeds produced in cones. These highly resistant structures are capable of waiting for a favorable environment before germinating. Approx- 400 million years ago 4- Angiosperms- Seeds protected by fruits and the presence of flowers with a need for pollinators. Approx- 135 million years ago

Alternation of Generations

Alternation of Generations 2 multicellular individuals alternate, each producing each other. sporophyte (2n)- produces spores through meiosis gametophyte (n)- produces gametes

Alternation of Generations Meiosis produces haploid spores in sporophytes. Spores go through mitosis and become gametophytes. Zygotes go through mitosis to produce sporophytes

Alternation of Generations Plants differ as to which generation is dominant. Archegonia→ female gametophyte Antheridia→ contain flagellated sperm Pollen Grains→mature sperm from seed plants

Other adaptations Cuticles Stomatas

Nonvascular Plants lack a specialized means of transporting water and nutrients lack true roots, stems, and leaves. Bryophytes is used to describe nonvascular plants. Gametophytes are the dominant generation. Sperm must swim in film of water to archegonia. May reproduce asexually, allowing them to live in harsh environments

Hornworts- Phylum Anthocerophyta “Herb” Live in moist, well-shaded trees May have symbiotic relationship with cyanobacteria Can reproduce asexually through fragmentation

Liverworts- Phylum Hepatophyta Terrestrial, epiphytic, or aquatic Majority have leafy bodies Thallose grow on creek banks after a fire

Marchantia Lower surface has hair like extensions called rhizoids. Rhizoids are for anchorage and limited absorption. Sexually and asexually reproduces.

Moss- Phylum Bryophyta 3 Distinct Classes: Peat Moss True Moss Rock Moss May live in almost any environment.

Moss reproduction May reproduce asexually through fragmentation Sexual reproduction is depicted to the right

Vascular Plants- Phylum Rhyniophyta Early vascular plants were homosporous Dominant sporophyte generation has several characteristics that allowed for successful colonization of land Xylem- water and dissolved minerals upward Phloem- sucrose and other organic materials throughout the plant Lignin- strengthens plants Now seed plants are heterosporous.

Seedless Vascular Plants Dominant through the Devonian period to the Carboniferous period

Club Moss- Phylum Lycophyta Dominant generation is the sporophyte Rhizome- horizontal underground stem 3 genera: Ground Pines-microphylls, homosporous Spike Mosses-macrophylls, heterosporous Quillworts-macrophylls, heterosporous

Horsetails- Phylum Sphenophyta Inhabit wet, marshy environments Strobilus Branches Node Leaves Rhizome Roots

Whisk Fern- Phylum Psilotophyta Live in southern climates as epiphytes or on the ground Have no leaves Sporangia found on short side branches

Ferns- Phylum Pterophyta Found in warm, moist, tropical regions Fronds are leaves of ferns divided into leaflets Can be used to remove formaldehyde from the air, expel tapeworms, and have medicinal value

Seed Plants -Devonian period -Seeds contain sporophyte embryo and stored food within a protective coat can remain dormant for hundreds of years -Heterosporous pollen grains contain multicellular male gametophyte

-No exterior water required for fertilization -Female gametophyte develops in ovule

Gymnosperms (naked seed) All have ovules and exposed seeds Carboniferous period- became dominant during Triassic period

Life cycle- see page 425 Figure 24.18

Conifers- Phylum Coniferophyta contains pines, spruces, firs majority bear cones phylum contains oldest tree and tallest tree tough needle-like leaves conserve water due to thick cuticle and recessed stomata

Phylum Coniferophyta sporophyte generation is dominant- pollen is wind blown and seed dispersal is in dispersal stage monoecious- tree produces both pollen and see used in construction, as fungal and insect repellant

Cycad- Phylum Cycadophyta native to tropical and subtropical areas resemble palms dioecious risk for extinction because of slow growth rate

Ginkgos- Phylum Ginkgophyta 1 surviving species dioecious

Gnetophyta- Phylum Gnetophyta extremely diverse phylum all have similar xylem no archegonia (evidence to support them being closest relative to angiosperms) cones have similar construction

Angiosperms ovules always enclosed within diploid tissues DNA sequencing is being used to determine ancestry 2 classes Monocotyledones- monocots- 1 seed leaf in seeds. Corn, tulips, and pineapples are examples Eudicotyledones- dicots- 2 cotyledones in seeds. Strawberries, cactus are examples.

Monocots Dicots One Cotyledon Two Cotyledon Flower parts in threes or multiples of three Flower parts in fours or multiples of fours Usually herbaceous Woody or herbaceous Usually parallel venation Usually net venation Scattered bundles in stem Vascular bundles in ring Fibrous root system Taproot system

Flower parts Sepals- (calyx) protect the flower bud before it opens. May fall off or remain attached. May be green or colored Petals- (corolla) attract a particular pollinator. Very diverse Stamens- consist of the anther, saclike, and filament (slender stalk) Carpel- vaselike- made of stigma, enlarged sticky knob; style, slender stalk; ovary, enlarged base that encloses one or more ovule. Ovule becomes seed and ovary becomes fruit Flowers may or may not have all the above parts (incomplete)

Life cycle- see page 430 Figure 24.26