Plant Diversity I: How Plants Colonized Land - PowerPoint PPT Presentation

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Plant Diversity I: How Plants Colonized Land

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  1. Plant Diversity I: How Plants Colonized Land Kingdom - Plantae nonvascular vascular (xylem/phloem) (water) (food)

  2. Nonvascular Division - Bryophyta mosses liverworts

  3. vascular Seedless Seed horsetails club mosses ferns

  4. seed gymnosperm angiosperm (Naked) (Covered) Ginkgo Gnetophyta Cycads Conifers

  5. Angiosperm Anthophyta Monocots Dicots

  6. phyte - plant arch - female epi - upon anth - male Plant Characteristics: 1. Structure: multicellular – (many celled) photosynthetic – (autotrophic) specialized – cells and tissues

  7. 2. Pigments: chlorophyll a chlorophyll b carotenoids

  8. 3. Storage polysaccharide (carbohydrate) – amylose starch Structural polysaccharide (carbohydrate) – is cellulose Strengthening agents: pectin lignin

  9. 4. Sporic life cycle: Alternation between diploid sporophyte and haploid gametophyte

  10. 5. Reproduction: embryo is multicellular (many-celled) housed in multicellular gametophyte tissue • meiosis in diploid (2n) sporophyte yields single celled, haploid (n) spores • then, cells in the gametophyte form gametes (sperms/eggs)

  11. sperm and egg meet - fertilize to form new diploid (2n) sporophyte (In animals there is no equivalent to gametophyte in plants)

  12. Nonvascular plants – bryophytes includes mosses, liverworts, and hornworts

  13. gametophyte is dominant • sporophyte is reduced • all other plants – • sporophyte is dominant (plant) • gametophyte is reduced

  14. Spores: homospory - one form of spore heterospory - 2 distinct types of spores • Small spores - microspores give rise to microgametophytes (male) (in seed plants – the pollen)

  15. megaspores – give rise to megagametophytes (female) • (in the ovule, located in the ovary of the flower)

  16. Bryophytes - mosses, liverworts, and hornworts • require water to reproduce (sperm swims) • conducting/supporting tissue? no, therefore size is limited

  17. anchorage – threadlike rhizoids Rhizoids are not used for absorption of water • cannot tolerate pollution • therefore they may be an indicator species

  18. liverworts: name from the fact they were once used to treat liver disease • wort - herb • leafy, gametophyte body - thallus thallus

  19. example of liverwort - Marchantia • pore-like stomata (exchange of gases)

  20. Asexual: 2 ways • fragmentation - parts grow into complete gametophyte • gemmae - form cups

  21. Sexual: 2 kinds of gametangia 1. egg-forming - archegonia produces stalked archegoniophores

  22. 2. sperm-forming - antheridia produces stalked antheridiophores • may be monoecious (one house) or dioecious (two houses) • sperm are splashed against archegonia

  23. upon fertilization – new diploid sporophyte produces sporangia meiosis (reduction division) produces haploid spores which develop into new gametophytes

  24. Mosses: most numerous and most common of the bryophytes • withstand drying conditions by “drying out” • ground cover in tundra (arctic) • importance - pioneer (colonizing) plants

  25. peat - Sphagnum for mulching (flavor in scotch whiskey) Moss gametophyte - protonema (similar to filamentous green algae) gametophyte

  26. sporophyte – capsule (which is spore-filled) operculum (cap) falls away releasing haploid spores • may produce 50 million spores sporophyte

  27. Class Musci - mosses capsule sporophyte gametophyte

  28. Vascular Plants - tracheophytes (tube plants)

  29. contain vascular tissue: xylem (conducts water) and phloem (conducts food)

  30. horizontal stems - rhizomes • water conducting elements (tube-like) - tracheids

  31. Early: club mosses / horsetails (ground pine) (scouring rushes) • cone - strobilus at end of branches

  32. Pterophyta - ferns • leaves which emerge above ground from the rhizomes - fiddleheads

  33. spores produced in sporangia • clustered into sori (sorus)

  34. fern gametophyte - prothallus - heart-shaped (short lived) • sperm escape from antheridia and swim to archegonia where fertilization occurs • the embryo develops into sporophyte (plant)

  35. Seed Plants: • came about due to climate changes – geological changes • (upheavals) - drying, cooling trends • female gametophyte fully enclosed in sporophytic tissues for protection

  36. Reproductive adaptations: • different spores – heterosporous • pollen - minute, resistant – carried from one plant to another by air and water currents or animals

  37. the pollen grain contains a generative cell which gives rise to 2 sperm cells and a tube cell which directs the growth of the pollen tube after pollination has occurred

  38. pollen tubes literally digest their way to the female gametophyte, no water is necessary

  39. Seeds: consist of embryo • region of stored food hardened seed coat

  40. gymnosperm means “naked seed”

  41. Division - Ginkgophyta • one species left - Ginkgobiloba

  42. thought to be extinct – therefore a “living fossil” • common name – maidenhair tree • living Ginkgo found on grounds of oriental temple • (year 1946) • now commonly cultivated as decorative plants

  43. sheds leaves in autumn • primitive trait – swimming sperm • trees have separate sexes - dioecious

  44. Division – Cycadophyta - cycads (palm-like) • common in time of dinosaurs • today live in tropics

  45. sperms produced in strobili (cone-like) • swimming sperm

  46. Division - Gnetophyta • have water-conducting xylem vessels within stem • (other gymnosperms have water-conducting tracheids)

  47. Welwitschia – description - twisted • Where do they grow? African desert

  48. Division - Coniferophyta • examples: pine, firs, spruce, hemlock

  49. biome - taiga • remain green - evergreen • male pollen cones • female ovulate cones