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Non-Vascular Plants and Ferns

Non-Vascular Plants and Ferns

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Non-Vascular Plants and Ferns

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  1. Non-Vascular Plants and Ferns

  2. (a) Chara, a pond organism 10 mm 40 µm (b) Coleochaete orbicularis, a disk- shaped charophycean (LM) Evolution of Land Plants • Land plants evolved from green algae • The green algae called charophyceans are the closest relatives of land plants • Comparisons of both nuclear and chloroplast genes • Point to charophyceans as the closest living relatives of land plants

  3. Origin and Diversification of Plants • Fossil evidence indicates that plants were on land at least 475 million years ago • Whatever the age of the first land plants those ancestral species gave rise to a vast diversity of modern plants

  4. Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Angiosperms Gymnosperms Liverworts Hornworts Charophyceans Pterophyte (ferns, horsetails, whisk fern) Lycophytes(club mosses, spike mosses, quillworts) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Plant Evolution

  5. Bryophytes • Life cycles of mosses and other bryophytes are dominated by the gametophyte stage • Bryophytes are represented today by three phyla of small herbaceous (nonwoody) plants • Liverworts, phylum Hepatophyta • Hornworts, phylum Anthocerophyta • Mosses, phylum Bryophyta

  6. LIVERWORTS (PHYLUM HEPATOPHYTA) Gametophore of female gametophyte Plagiochila deltoidea, a “leafy” liverwort Foot Seta Sporangium Marchantia polymorpha, a “thalloid” liverwort Marchantia sporophyte (LM) 500 µm MOSSES (PHYLUM BRYOPHYTA) HORNWORTS (PHYLUM ANTHOCEROPHYTA) An Anthoceros hornwort species Polytrichum commune, hairy-cap moss Sporophyte Sporophyte Gametophyte Gametophyte Bryophytes

  7. Liverworts • Have no true roots or shoots • Non- vascular • Require water to reproduce • Have no or very little leaf structure • Cannot live in sporophyte form

  8. Hornworts • Free-floating aquatic plant, or land plant • No vascular tissue • No true leaves or roots • Can live in both gametophyte and sporophyte forms

  9. Mosses • Land plant • Most have no vascular tissue • Majority to life spent in gametophyte • Need water to breed • No leaves or roots • Sporophytes are capsules on stalks

  10. Vascular Plants • Vascular plants have two types of vascular tissue • Xylem and phloem • Xylem • Conducts most of the water and minerals • Includes dead cells called tracheids • Phloem • Distributes sugars, amino acids, and other organic products • Consists of living cells

  11. Vascular Plants • Vascular plants have roots • Are organs that anchor vascular plants • Enable vascular plants to absorb water and nutrients from the soil • May have evolved from subterranean stems • Vascular plants have leaves • Leaves are organs that increase the surface area of vascular plants, thereby capturing more solar energy for photosynthesis

  12. Vascular Plants • Two types of vascular plants: seedless and seeded • Seedless vascular plants form two phyla • Lycophyta, including club mosses, spike mosses, and quillworts • Pterophyta, including ferns, horsetails, and whisk ferns and their relatives • Modern species of lycophytes are relics from a far more eminent past • Are small herbaceous plants • Ferns • Are the most diverse seedless vascular plants

  13. LYCOPHYTES (PHYLUM LYCOPHYTA) Strobili (clusters of sporophylls) Isoetes gunnii, a quillwort Selaginella apoda, a spike moss Diphasiastrum tristachyum, a club moss PTEROPHYTES (PHYLUM PTEROPHYTA) Psilotum nudum, a whisk fern Equisetum arvense, field horsetail Athyrium filix-femina, lady fern Vegetative stem Strobilus on fertile stem FERNS HORSETAILS WHISK FERNS AND RELATIVES Seedless Vascular Plants

  14. Ferns • Like vascular plants but do not have seeds • Common in shady areas, diverse in the tropics • Have flagellated sperm that require water to reach the eggs

  15. Alternation of Generations • The seed plant life cycle contains both haploid and diploid stages • Diploid individuals are called sporophytes • Haploid individuals are called gametophytes • Does not happen in algae • May have evolved as an adaptation to harsh environments • Haploid cells divide into a cluster of cells before meiosis

  16. Gametophytes(male and female)n Mitosis Mitosis Sporesn Gametes(sperm and eggs)n HAPLOID Fertilization Meiosis DIPLOID Zygote2n Mitosis Sporophyte2n Alternation of Generations

  17. 5 Mitosis anddevelopment Sperm (n) (released fromtheir gametangium) Spores(n) 1 Gametangiumcontaining the egg (n) (remains within gametophyte) Gametophytes(n) Egg HAPLOID Meiosis Fertilization DIPLOID Sporangium Stalk 2 4 Zygote(2n) Gametophyte(n) 3 Mitosis anddevelopment Sporophytes (growing from gametophytes) Dominant Gametophyte • Mosses have a dominant gametophyte stage

  18. Sperm (n) 5 Mitosis anddevelopment Spores(n) 1 Gametophyte (n) (underside) Egg (n) Fertilization HAPLOID Meiosis DIPLOID Sporangia 2 4 Zygote(2n) 3 Mitosis anddevelopment New sporophyte growingout of gametophyte Sporophyte (2n) Dominant Sporophyte • Most plants have a dominant sporophyte stage

  19. Seeded Vascular Plants • Gymnosperms- conifers, cycads, and ginkgo • Angiosperms- flowering plants