1-13-10_Non-Seed Plants

1-13-10_Non-Seed Plants - Chromalveolata Rhizaria Trends in...

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1 Archaeplastida Primary endosymbiosis Excavata Rhizaria Chromalveolata Independent secondary endosymbiosis events Charophycean ancestor Charophyceans Bryophytes Pteridophytes Gymnosperms Angiosperms (mosses, etc.) (ferns, etc.) (conifers, etc.) (flowering plants) Trends in plant complexity: non-seed plants seed plants vascular plants land plants Reproduction by flowers Dispersal by seeds Presence of vascular tissue Basic land plant attributes Trends in plant complexity: Bryophytes Mosses are very abundant, very important ecologically Bryophytes have the basic ‘land plant’ attributes: • apical meristems • multicellular, dependent embryos • alternation of generations • multicellular gametangia • walled spores Three phyla (“divisions”): Hepatophyta (liverworts) Athocerophyta (hornworts) Bryophyta (mosses) Trends in plant complexity: Bryophytes Three phyla (“divisions”): Hepatophyta (liverworts) Athocerophyta (hornworts) Bryophyta (mosses) Bryophytes are very ancient; probably were the first land plants • liverworts, hornworts are reasonably good models of how early land plants looked and functioned
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2 Fig. 29-7 Origin of land plants (about 475 mya) 1 2 3 1 2 3 Origin of vascular plants (about 420 mya) Origin of extant seed plants (about 305 mya) ANCES- TRAL GREEN ALGA Liverworts Hornworts Mosses Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms Seed plants Seedless vascular plants Nonvascular (bryophytes) Land plants Vascular plants Millions of years ago (mya) 500 450 400 350 300 50 0 Trends in plant complexity: Bryophytes Bryophytes have the basic ‘land plant’ attributes: • apical meristems • multicellular, dependent embryos • alternation of generations • multicellular gametangia • walled spores All bryophytes are small and highly dependent on plenty of water. • no vascular tissue (except simple forms in mosses) • need to be thin so all cells are close to sources of water and dissolved mineral nutrients (usually only a few cells thick) • usually have no specialized supporting structure (‘hardened’ cell walls); cannot grow more than a few cm tall (a few mosses get taller) flagellated sperm that need to swim to reach the egg, so they can reproduce only if a film of water is present Many bryophytes can live in seasonally dry areas (dormant while dry), but all need liquid water for reproduction.
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1-13-10_Non-Seed Plants - Chromalveolata Rhizaria Trends in...

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