Land plants: origins seedless plants Biol 121, Fall 2010, Tom Buckley 22 Sep 10
Phylogeny of land plants Brown and golden algae green algae
land plants 2n embryo
Probable ancestor: algae at lake edges (periodic drying)
Plant evolution aquatic ancestors land plants nonvascular plants seedless vascular plants vascular plants seed plants naked-seeded plants vessel-seeded plants green algae mossesfernsconifersflowering plants
Diversification of land plants # of spp 9, ,000 1,200 12, ,000 Fig 29.7 seedless plants seed plants
Diversification of land plants gametophyte = dominant sporophyte = dominant Fig 29.7
Characters of land plants walled spores produced in sporangia function of spores?
Characters of land plants apical meristems function of apical meristems?
Phylum Bryophyta (mosses) Phylum Hepatophyta (liverworts) Phylum Anthocerophyta (hornworts)
liverworthornwort
bryophyte anatomy hydroidsleptoids stem x.s. photosynthetic cells leaf x.s.
bryophyte anatomy photosynthetic cells leaf x.s. epidermis hornwort stoma
Bryophyte life cycle Fig 29.8
gametes produced in gametangia male: antheridia female: archegonium Bryophyte life cycle Fig 29.8
Bryophyte life cycle Fig 29.8
Bryophyte life cycle Fig 29.8
Seedless vascular plants Phylum Pterophyta (ferns, horsetails & relatives) Phylum Lycophyta ("club mosses" & relatives)
Isoetes sp. ("quillwort")tree fern
Equisetum sp. ("horsetail")
Seedless vascular plants: new features Vascular tissue makes large plants possible Sporophyte is dominant Sporophylls: modified leaves that bear sporangia permits complex reproductive structures nonvascular vascular
Fern life cycle
Sporangium: spore container
Sorus (pl. sori) = cluster of sporangia indusiumsorus
Sori
Horsetails (Equisetum)Strobilus (pl. strobili) = cluster of sporangia
sporophyll sporangium Horsetails (Equisetum)
Whisk fern (Psilotum) Synangium = cluster of 3 fused sporangia
Spike moss (Selaginella) Phylum Lycophyta Club moss (Lycopodium)
Q: What is the ploidy level of the tissues indicated by arrows? (a)n n (b)n 2n (c)2n n (d)2n 2n AB Moss (Phylum Bryophyta) A B
Q: In which of the following are gametes haploid? (a)Phylum Bryophyta (b)Phylum Pterophyta (c)Phylum Lycophyta (d)All of the above
Alternation of generations meiosis diploid syngamy haploid diploid haploid meiosis syngamy