BIOL 1202 Lecture Notes - Lecture 10: Gnetophyta, Cycad, Ginkgo Biloba

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22 Feb 2017
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Chapter 30 plant diversity ii: the evolution of seed plants. Concept 30:1: seeds and pollen grains are key adaptations for life on land. Characteristics common to all seed plants: seeds, reduced gametophytes, heterospory, ovules, pollen. Gametophyte/ sporophyte: figure 30. 2, gametophytes of seed plants develop within the walls of spores retained within tissue of the parent sporophyte, no longer dependent on water for fertilization. Ovules and production of eggs: an ovule consists of a megasporangium, megaspore, and protective integuments, figure 30. 3a ovule to seed. Pollen and production of sperm: microspores develop into pollen grains. Contain male gametophyte: pollen can be dispersed by air or animals, eliminates the need for water in fertilization. It gives rise to a pollen tube that discharges sperm into the female gametophyte within the ovule: figure 30. b ovule to seed. A seed: develops from the whole ovule. Single spore type (vascular tissues, diploid dominance, and cuticle with stomata do apply)

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