1 / 80

Vascular Plants

Vascular Plants. Generalized life cycle. Moss life cycle. Spore -> Gametophyte. Gametophyte -> Zygote. Zygote -> mature sporophyte. Sporophyte -> spores. Vascular Plants. Vascular Plants. Branching sporophyte in Silurian First vascular plants in Devonian. First flowering plants.

janet
Download Presentation

Vascular Plants

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Vascular Plants

  2. Generalized life cycle

  3. Moss life cycle

  4. Spore -> Gametophyte

  5. Gametophyte -> Zygote

  6. Zygote -> mature sporophyte

  7. Sporophyte -> spores

  8. Vascular Plants

  9. Vascular Plants • Branching sporophyte in Silurian • First vascular plants in Devonian First flowering plants Age of Ferns First fossil of non-algal land plant in Silurian - 430 mya Liverwort spore tetrads - end of Ordovician

  10. Fossils • Probable embryophyte spores at 450 Ma • Cooksonia fossils in Silurian (ca. 430 Ma)

  11. Plants like Cooksonia lacked a vascular system • Dichotomously-branching axes • Terminal sporangia • No roots or leaves

  12. Over-time became larger, more complex, and acquired a vascular system Time

  13. Living vascular plants (Tracheophytes) • Stems and roots (often leaves)

  14. Living vascular plants (Tracheophytes) • Stems and roots • Sporophytes dominate the life-cycle

  15. Sporophyte dominance Gametphyte Tree fern

  16. Why sporophyte dominance? • Spore dispersal by wind: aided by height • Competition for light (gametophyte constrained by the need for water)

  17. Living vascular plants (Tracheophytes) • Stems and roots • Sporophytes dominate the life-cycle • A vascular (transport) system

  18. Vascular system • Xylem (water transport) and phloem (metabolite transport) Stem Vascular Bundle Xylem Phloem Root

  19. Xylem • Composed primarily of Tracheids • Elongated, dead, cells • Cell wall impregnated with lignin • Transport of water from soil to leaves

  20. Phloem • Transport via sieve elements • Elongated, living cells • Transport of sugars, hormones, etc.

  21. 3 Major groups of Vascular plants • Seed plants (gymnosperms and angiosperms) • Lycophytes (club mosses and their relatives) • Moniliforms (ferns and fern allies)

  22. Major tracheophyte taxa • Seed Plants (ca. 290,000 species) • Lycophytes (ca. 1,100 species) • Ferns and allies (ca. 11,000 species) Tracheophytes that are not seed plants are sometimes called “pteridophytes”

  23. Vascular plant phylogeny bryophytes lycophytes Ferns + Seed plants Microphylls Cooksonia Megaphylls Vascular tissue, Roots Branched sporophyte

  24. Organ systems origins • Stems - dichotomous branching

  25. Organ systems origins • Stems • Leaves • Microphylls

  26. Organ systems origins • Stems • Leaves • Microphylls • Megaphylls

  27. Organ systems origins • Stems • Leaves • Microphylls • Megaphylls • Roots

  28. Homospory versus Heterospory

  29. An important variation: Heterospory Megasporangium Microsporangium Lycopodium (homosporous) Selaginella (heterosporous)

  30. Heterospory • Microspores and megaspores produced in different sporangia on different leaves (microsporophylls; megasporophylls) • Microspores grow into male gametophytes • Megaspores grow into female gametophytes - remains within spore wall

  31. Homospory Diploid Haploid sperm zygote egg sporophyte gametophyte spore

  32. Heterospory Diploid Haploid zygote egg sperm sporophyte female gametophyte male gametophyte microspore megaspore

  33. Heterospory evolved many times. Why? • Increases potential for outcrossing • Specialization of function between micro- and megagametophyte permits greater efficiency (less cost)

  34. 3 Major groups of Vascular plants • Seed plants (gymnosperms and angiosperms) • Lycophytes (club mosses and their relatives) • Moniliforms (ferns and fern allies)

  35. Moniliforms Spermatophyta Lycophyta Pryer et al. 2001

  36. Lycophytes • 380 Ma old • 1100 spp. • Microphylls only • Sister group to the other living vascular plants

  37. Lycophytes • 380 Ma old • 1100 spp. • Microphylls only lycophytes Ferns + Seed plants Microphylls Megaphylls

  38. Lycopodium Clubmoss (Lycopodium) Lycophytes Isoetes Selaginella Selaginella

  39. Carboniferous lycopodsup to 40 m Sigillaria Lepidodendron

  40. Lycopodium life cycle I Sporophyte makes sporangia often in a “strobilus” Sporangium

  41. Lycopodium life cycle I Sporophyte makes sporangia often in a “strobilus” Sporophyll Sporangium

  42. Lycopodium life cycle II Spores dispersed by wind: germinate into a minute gametophyte Spore Thallus Spore Rhizoids

  43. Lycopodium life cycle III • Gametophyte produces archegonia and antheridia (bisexual) • Biflagellate sperm fertilize egg cells • New sporophyte grows Archegonial neck

  44. Lycophyte diversity • 3 Major groups • Lycopodiaceae (club mosses) • Selaginella • Isoetes

  45. Lycopiaceae • Approximately 400 species • Dominated Carboniferous, up to 40 m tall • form much of modern coal • Homosporous • Archegonia and Antheridia can take 6-15 years to mature

  46. Selaginella • Approximately 700 extant species • Heterosporous • Moist habitats or "resurrect" Selaginella umbrosa

  47. Isoetes • Approximately 200 species • Grow in water or dried pools

  48. Moniliforms Spermatophyta Lycophyta

  49. Ferns and fern allies (moniliforms) • Includes ferns (Pterophyta) and two small groups (Psilophyta and Sphenophyta) • ca. 12,000 spp. • Homosporous or heterosporous • Megaphylls (lost in Psilophyta and Sphenophyta) • Ecologically important especially as tropical epiphytes

More Related