SFR 107 Lecture Notes - Lecture 8: Pollination, Eudicots, Tracheid
12 Dec 2016
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Document Summary
Great diversity in form of any plant group. Gymnosperms were the dominant plant group for 100 million years. Early angiosperms were likely shrubs of low stature. Likely vary flexible in form and tolerant to stress. Seeds develop inside a fruit: formed from parental tissue, soft fruits, hard fruits. Flower: female gametophyte and egg(s) enclosed, zygote and embryo develop in a protective ovary. Co-evolved with animal pollinators and dispersal agents. Investment of resources: attractants: flowers, volatile chemicals, fruits. Gymnosperms (also ferns and fern-relatives) use tracheids: spindle-shaped, closed ends, water must pass through pits. Angiosperms evolved vessels: stacked into long tubes" with open ends between cells. Cells with ends removed stack in long columns. More efficient than the closed-end tracheids of ferns and gymnosperms. Rapidly became dominant in all but cold temperate forest and boreal biomes: tropical forests, warm to cool temperate forests, savanna grasslands. Radiated to an unprecedented diversity of families and species.
