01:119:115 Lecture 8: Biology- Lecture 8 (Plant Diversity II- Evolution of Seed Plants - Chapter 30.1-30.3)(1)
13 Jul 2016
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Plants are in: domain eukarya 3rd supergroup archaeplastida. Characteristics of seed plants: adaptations to life on land. Seeds + pollen grains are key adaptations for life on land. Common characteristics to all seed plants: reduced gametophytes, heterospory, ovules, pollen, seeds, reduced gametophytes, microscopic, develop from spores within tissues of the parent sporophyte, totally dependent on sporophyte generation dominant. Integument = layer of sporophyte tissue envelopes and protect megasporangium. Angiosperm 2 integuments: female gametophyte develops from megaspore & produces 1 or more eggs, pollen and production of sperm, pollen grains. Consist of male gametophyte enclosed within pollen wall. Tube cell will produce a pollen tube. Most gymnosperm & all angiosperm sperm do not have flagella. Can colonize dry habitats: evolutionary advantage of seeds. Seedless plants spore is only protective stage. A seed = a sporophyte embryo, along with its food supply, packaged in a protective coat. Seeds exposed on sporophylls form cones (strobili)
