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Published byEgbert Lawrence Modified over 9 years ago
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I. Bryophytes - mosses = many plants growing in a tight pack. No waxy cuticle and do not retain developing embryos w/i mother plant’s gametangium. Need water to reproduce; sperm are flagellated, must swim through water to reach eggs No vascular tissue to carry water(grow low to ground) and lack lignin Like damp, shady places Green spongy plant = gametophyte (male & female are separate plant shoots)(n) Taller brown shoot with a capsule, grows out of gametohyte = sporophyte (2n)
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Alternation of Generations - 2 generations that take turns producing each other Gametophytes produce eggs and sperm; must unite to form a zygote, which forms new sporophytes. Sporophytes produce spores Spores can develop into a new organism without uniting, & have a tough coat to resist harsh environments. The new organism then produces gametophytes again. Gametophyte = larger more obvious plant in mosses
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Moss- Gametophyte (left) and Archegonium (female gametophyte) (right) (Antheridium = male gametopyte.)
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Sporophyte generation (left) and Sporangia (right) Moss is cool! E.C. for bringing in moss with both generations. (In late spring.)
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II. Ferns - diverse with 12,000 species, most in tropics, many in temperate woodlands of U.S. Evolution of vascular tissue (xylem and phloem) Sperm are still flagellated-must swim through a film of water to fertilize eggs Are still seedless - have spores During Carboniferous Period, ferns in swamp forests converted to coal - (black sedimentary rock made up of fossilized plant material)
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Alternation of Generations in ferns. Sporophytes are diploid and gametophytes are haploid Sporophyte is the dominant stage in ferns. (Gametophyte was dominant in mosses) Heart shaped gametophyte = prothallus
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