BIOL10005 Lecture Notes - Lecture 21: Heterospory, Sporophyte, Secondary Growth

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Motile gametes, dependent on water -> primitive feature. Sporophyte and gametophyte are independent of each other; different life form. Gametophyte supports the early stages of the sporophyte: seed plants, cycads. Two types of spores (heterospory): megaspores (in ovules) and microspores (pollen, males), in conifers both are born as cones. Male gametes are transported in pollen (process of pollination) Embryonic plant encased within a protective coating, typically resourced with stored food. Vascular cambium is a meristem that produces additional vascular tissue (xylem & phloem) Secondary growth increases the girth of a stem by adding wood and bark. Essential for development of shrubs and trees. Sporophyte produces two different spores by meiosis: megaspore & microspore (n) Megaspore develops to megagametophyte -> egg / microspore -> macrogametophyte -> sperm. Pollen grains are transported to the ovule prior to sperm cell development. Sperm cells do not require free water. Pollination and fertilization are separated in time.

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