Plant Diversity Jewett


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Plant Diversity lecture covering Mosses, Ferns, Gymnosperms and Angiosperms, based on Chapters 29 and 30 from Campbell & Reece "Biology" 8th edition (International). For ACS Biology 10, Sofia Bulgaria. March 2010

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  • Vascular tissue – cells joined into tubes to transport water & nutrients throughout a plant Seeds – an embryo and a food supply, surrounded by a protective coat (CR p 618)
  • Short because they are non-woody and can’t support themselves, also no vascular tissue to transport water/nutrients Moist environment because the sperm have to swim to egg Sexual reproduction requirements keep mosses close to each other (sperm has to swim) Gametophytes are dominant part of life cycle (the one you think of as “mossy”)
  • Elevation of stalk (seta) helps spore dispersal Sporophytes have stomata to regulate water loss (also found in all vascular plants)
  • You’d have to dig around on the ground on your hands & knees to see fern gametophytes, which are the dominant form in mosses Lignified stems allow plants to get taller – arms race for sunlight! Non-woody plants rarely get more than 20cm tall. Lignin also allows real roots – get water, nutrients, and anchor (needed if you’re getting TALL)
  • Fern Frond Sori (sing: sorus) where the spores come from Ferns took carbon out of atm 350MYA, cooled atm, turned to coal, burned, CO2 in atm, warming in atm
  • Seed plants about 360 MYA Seed = detachable, mobile womb! (embryo plus support structure)
  • Microscopic gametophytes allow eggs to stay inside, protected from drying out and UV stress Heterospory (male and female spores) – megaspore are female (big pine cones), microspores are male (tiny cones)
  • Wind-pollinated flowers usually lack petals (grasses) Stamen – produce pollen Carpel – female parts…stigma catches pollen, style delivers, ovary receives
  • Plant Diversity Jewett

    1. 1. Plant Diversity (Chapters 29 & 20) All you ever wanted to know about plants…but were afraid to ask. Jeff Jewett American College of Sofia March 2010 Version 1.0
    2. 2. Land Plants Happy 475,000,000 birthday! <ul><li>Land is great!  </li></ul><ul><ul><li>It’s so sunny! </li></ul></ul><ul><ul><li>Make me some sugar! (More CO2! More nutrients) </li></ul></ul><ul><ul><li>No one is eating me (at first) </li></ul></ul><ul><li>Land is a bummer…  </li></ul><ul><ul><li>“ This is heavy, man.” </li></ul></ul><ul><ul><li>“ So…very…thirsty…” </li></ul></ul><ul><ul><li>“ Pass the sunblock!” </li></ul></ul>
    3. 3. Major groups of land plants <ul><li>Nonvascular </li></ul><ul><ul><li>Bryophytes (Mosses, Liverworts, Hornworts) </li></ul></ul><ul><li>Vascular (93%) </li></ul><ul><ul><li>Ferns </li></ul></ul><ul><ul><li>Seed Plants </li></ul></ul><ul><ul><ul><li>Gymnosperms (Conifers, Ginkos, Cycads) </li></ul></ul></ul><ul><ul><ul><li>Angiosperms (Flowering plants) (90%) </li></ul></ul></ul>
    4. 4. Moss – the oldest land plant <ul><li>120 families, 700 genera, 10,000 species </li></ul><ul><li>Non-vascular </li></ul><ul><li>Seedless, no flowers, non-woody (no lignin) </li></ul><ul><li>Require water for reproduction </li></ul><ul><li>Usually short (< 15 cm) </li></ul><ul><li>Usually found in moist environments </li></ul> мъх Gametophytes (haploid, 1N) are dominant part of life cycle
    5. 5. <ul><li>Gametophyte (N) is dominant (unlike vascular plants) Sporophyte (2N) is short-lived parasite </li></ul>
    6. 6. Moss Sex? <ul><li>Alternation of generations </li></ul><ul><ul><li>Gametophytes (n)  gametes (n)  zygote (2n)  Sporophyte (2n)  spore (n)  back to gametophyte. </li></ul></ul>
    7. 8. Moss Life Cycle Animation
    8. 9.
    9. 10. Ferns (Filicinophyta) <ul><li>420 MYA </li></ul><ul><li>woody (lignified) stems…can be tall! </li></ul><ul><li>Vascular tissue </li></ul><ul><li>Roots & Leaves </li></ul><ul><li>Dominant form: sporophyte (2N) </li></ul><ul><li>seedless </li></ul>ПАПРАТ
    10. 11. Vascular Tissue <ul><li>Xylem – moves water up from roots  leaves </li></ul><ul><li>Phloem – moves “phood” down from leaves to rest of plant </li></ul>
    11. 12. Global Impact of Seedless Vascular Plants (ferns and such) <ul><li>Vascular tissue & lignin allowed TALL plants </li></ul><ul><li>Giant ferns during ~350MYA formed first forests </li></ul><ul><li>Big increase in photosynthesis </li></ul><ul><li>CO 2 in atm dropped 80%!!! </li></ul><ul><li>Global cooling, glaciers (brrr) </li></ul><ul><li>Irony: remains of these plants became fossil fuels, burned today  cause global warming. D’oh! </li></ul>http:// Sori: where spores form
    12. 13. Fern Life Cycle
    13. 14. Seed plants <ul><li>300 MYA – swamps began to dry up, giving new “seed plants” advantage </li></ul><ul><li>“Naked” (gymnosperms) and covered seeds (angiosperms) </li></ul><ul><li>Seed: embryo with a food supply, in a protective coating </li></ul><ul><li>Seeds are a detachable, mobile, womb (with embryo)  </li></ul>
    14. 15. New & Improved! <ul><li>Shrunken gametophytes (microscopic) </li></ul><ul><li>Male/female spores </li></ul><ul><li>Ovules/pollen </li></ul>
    15. 16. Comparison of life cycles – learn this!
    16. 17. Pollen <ul><li>Male gametophyte surrounded by protective layer </li></ul><ul><li>Sperm swimming through water (ferns & moss) can only go a few cm </li></ul><ul><li>Pollen can go hundreds of KM by wind or animal </li></ul>
    17. 18. Seeds vs Spores Protective coat No protective coat Food supply – can lay dormant much longer No food supply Multi-cellular: embryo plus food supply plus seed coat Single-celled: embryo 2N 2N SEEDS SPORES (mosses & ferns)
    18. 19. Gymnosperms <ul><li>~305 MYA (150 MY before flowering plants!) </li></ul><ul><li>Some gymnosperms took advantage of drier conditions with waxy cuticles and needle-like leaves </li></ul>
    19. 20. Gymnosperm Diversity Phylum Ginkgophyta Phylum Gnetophyta Image: University of Wisconsin – Madison Botany Phylum Coniferophyta Phylum Cycadophyta Image: University of Wisconsin – Madison Plant Systematics Collection
    20. 21. <ul><li>Male pine cones (sporangia, pollen-producing) </li></ul><ul><li>Male & female pine cones </li></ul>
    21. 22. Angiosperms (Flowering Plants) <ul><li>250,000 species (90% of all living plants!) </li></ul><ul><li>Flower – specialized sex part </li></ul><ul><li>Sepal, Petal, Stamen, Carpel </li></ul>
    22. 23. Fruit <ul><li>Protect dormant seeds </li></ul><ul><li>Aid in dispersal </li></ul>
    23. 24. Monocot & (Eu)Dicot <ul><li>Cotyledon – seed leaf in the embryo </li></ul><ul><li>Monocots = one seed leaf </li></ul><ul><li>Dicots = two seed leaves </li></ul>
    24. 25. Yes No No No Flower / Fruit Pollen Pollen Sperm (needs H2O) Sperm (needs H2O) Male Gamete (1N) Seed Seed Spore Spore Seeds / Spores (2N) Yes Yes Yes No Woody Stem (with lignin) Yes Yes Yes No Vascular Tissue Sporophyte Sporophyte Sporophyte Gametophyte Dominant Life Form Angiosperms Gymnosperms Ferns Mosses