01:119:116 Lecture Notes - Lecture 8: Pollen Tube, Sporangium, Megaspore
22 Apr 2016
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Plant diversity ii: evolution of seed plants lecture. Characteristics of seed plants: adaptations to life on land. Seeds + pollen grains are key adaptation for life on land. Develop from spores within tissues of the parent sporophyte. Totally dependent on sporophyte generation dominant. Production of two different types of spores. Megasporangia megaspores give rise to female gametophytes. Microsporangia microspores give rise to male gametophytes. Ovule = megasporangium (2n) + megaspore (1n) + integuments (2n) Integument = layer of sporophyte tissue envelopes and protects megasporangium. Female gametophyte develops from megaspore and produces 1+ eggs. Consist of male gametophyte enclosed within pollen walls. Tube cell will produce a pollen tube. Sporopollenin in pollen wall protects pollen grain from environment. Pollination = transfer of pollen to part of a plant containing the ovules . Not the same as fertilisation carried by wind/animals. Sperm not dependent on water for dispersal. Most gymnosperms and all angiosperm have no flagella.
