BIOL 2P93 Lecture Notes - Lecture 4: Cork Cambium, Vascular Cambium, Conifer Cone
13 Jul 2016
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Document Summary
Seed development by land vascular plants: important role in development in the reproduction and success of gymnosperms and angiosperms, seed plants dominant biological niches on land. A small embryonic plant enclosed in a covering called the seed coat usually with some stored food. Product of ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the parent plant. Seed production is an extreme form of heterospory that has been modified to form the ovule. Gymnosperm ovule consists of a nucellus (megasporangium structure where megaspores are produced) enveloped by one integument tissue layer with a micropyle. When the ovules are ready to be fertilized, the nucellus will contain a megagametophyte composed of nutritive tissue and archegonia. After fertilization, the integument develops into the seed coat, all seeds contain ready made stored food. Retention of megaspores within megasporangium: megasporangium no longer releases spores. Reduction of the number of megaspore mother cells in each megasporangium to one.
