01:119:116 Lecture Notes - Lecture 8: Gametangium, Charophyta, Phragmoplast
30 Sep 2018
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Document Summary
Charophytes closest relatives of land plants: adaptations if charophytes for life on land, many live in shallow water at edges of ponds and lakes. Natural selection favors individuals that can survive periods not being submerged: sporopollenin. Similar adaptation in plant spores: derived characters of charophytes and land plants, rings of cellulose-synthesizing proteins. In pm, synthesize cellulose of cell walls: structure of flagellated sperm, formation of phragmoplast. Group of microtubules between daughter nuclei during cell division. Gives rise to new cross walls- separate daughter cells: derived characters of land plants. Fig 29. 3: multicellular, dependent embryos, 2n embryo (sporophyte) retained within female gametophyte, placental transfer cells. Nutrients from parent to embryo: land plants= embryophytes. Embryos dependent on parent: walled spores produced in sporangia. Fig 29. 3: sporangium- multicellular organ in sporophyte. Produces spores: sporocytes- diploid cells in sporangium. Meiosis haploid spores: spores - reproductive cells. Mitosis multicellular gametophytes: spore walls contain sporopollenin.
