BOTANY 130 Study Guide - Final Guide: Pollen Tube, Ovule, Megaspore
Document Summary
Oogamous: large nonmotile eggs, and small swimming sperm. Most homosporus,* heterospory only in selaginella, isoetes and water ferns (heteropsory results in reduced size gametophytes) characteristic of seedless only. Heterosporus: microspores (make male gametophytes) and megaspores (make female gametophytes) on same stobilus, but in different sporangium, therefore makes two kinds of unisexual gametophytes and a sperm from one swims to the archegonia of the other and fertilizes it. Homosporous : one type of spore therefore gametophyte that has both archegonia and antheridia and are therefore bisexual. Increases potential for outcrossing (breeding with other) which will increase genetic variation. Micro- and mega- gametophyte are specialized for function means greater efficiency. Megagametophyts can give more nutrience to the offspring. Sporophytes have true leaves, roots and stems. Water required for reproduction: sperm swim through water to get to the archegonia. Carboniferous forest, fossil fuels (lepidendron also made fossil flues) Sporpohytes have true stems, roots and leaves. Sporophytes derives nutrience from gametophyte early in life.
