Ch. 29 Plantae

Ch. 29 Plantae - Eukaryotic Diversity: K. Plantae Chapters...

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Plant Diversity 1 BIOL 112 Eukaryotic Diversity: K. Plantae Chapters 29–30 BIOL 112 The “Crown Group” ± Three multicellular kingdoms K. Plantae K. Fungi K. Animalia ± All true multicellular organisms (differentiated cells) with multi-tissue body plan ± All make use of eukaryotic alternation of generations sexual cycle BIOL 112 BIOL 112 BIOL 112 Kingdom Plantae ± Multicellular, mostly macroscopic, mostly photoautotrophic ± Cell walls with cellulose ± Multiple tissue/cell types organized into stereotyped structures: stems, leaves and roots ± Some members vascularized (xylem and phloem) ± Most species terrestrial or secondarily aquatic ± At least 500,000 species ± Campbell discusses suggestion of combining green algae and plants into proposed K. Viridiplantae BIOL 112
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Plant Diversity 2 BIOL 112 BIOL 112 Plant Evolution ± Appear to have descended from green algae approx. 475 x 10 6 years ago ± Candidate ancestors are charophyceans advanced green algae — DNA, cell structure, biochemistry and chlorophyll similarities to plants Ref: McCourt, et al. (2004) Trends Ecol. Evol. 19: 661– 666. BIOL 112 BIOL 112 Remember the “X-Scheme” BIOL 112 Evolutionary Sequence ± Plant kingdom especially instructive ± Comparison of primitive to advanced groups shows clear sequence of evolutionary trends ± This sequence is associated with increasing ability of the plants to live on dry land, free from need for water film BIOL 112 ± From primitive to advanced plant taxa, see evolutionary trends: Increasing complexity of organization of body Increasing importance to the diploid phase of life cycle and decreasing importance to the haploid phase. This includes the appearance of embryo sporophyte plants Increasing independence from the need for free water film for fertilization and general life cycle ± Note: “primitive” in this context means “ancient” or “ancestor- like,” not bad or defective. “Advanced” means “unlike known or hypothesized ancestral form,” “derived,” not better
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Plant Diversity 3 BIOL 112 BIOL 112 BIOL 112 “Cryptogams” ± Primitive phyla in K. Plantae ± Do not produce seeds; mystery to early botanists how these reproduced ± We now know that these organisms release microscopic spores which germinate into gametophytes ± Informal category of cryptogams still applies to seedless plants (bryophytes, ferns, etc.) BIOL 112 Spore, instead of seed BIOL 112 BIOL 112 Phylum Bryophyta ± Primitive phylum ± Live in moist environments, need water film ± Haploid (gametophyte)-dominant life cycle; both gametophyte and sporophyte phases are multicellular ± Poor multicellular organization, no vascularization of tissues ± Dimorphic gametophytes: males produce sperm in antheridia ; females produce eggs in archegonia ± Sperm are poor swimmers and depend upon water splash to get to vicinity of archegonia ± Sporophyte is non-photosynthetic and depends upon gametophyte for nourishment and support
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Plant Diversity 4 BIOL 112 BIOL 112 Antheridium, producing sperm BIOL 112 Archegonium with egg BIOL 112 Moss gametophytes BIOL 112 Cross-section of moss gametophyte “leaf” BIOL 112
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This note was uploaded on 04/28/2010 for the course BIOL 102 taught by Professor Aufderheide during the Spring '10 term at Texas A&M.

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Ch. 29 Plantae - Eukaryotic Diversity: K. Plantae Chapters...

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