SeedPlants213-page9

SeedPlants213-page9 - A can always be identified from its...

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Seed-Dispersing Plants - 9 Ginkgophyta ( Ginkgo or Maidenhair tree) There is one living species within the Ginkgophyta, Ginkgo biloba. While fossil Ginkgoes are quite common, including in Washington, only Ginkgo biloba , a relict species, survives today substantially because it was preserved in Asian temple gardens for centuries as a revered plant. Some areas in China and Japan have Ginkgo groves with specimens over one thousand years old. The Ginkgo is a deciduous tree that grows to about 100' in height. There are two types of branches on Ginkgos: indeterminate branches, or long shoots, and determinant branches, or spur shoots. The spur shoots contain clusters of leaves each year. The short spur shoots are more common than the long shoots, so growth is slow and limited. The leaves of are fan-shaped, often with notch in center and pale green in color. Most are about 2" wide. They turn a vibrant gold in the autumn, and abscise around Halloween. The veins branch dichotomously, a unique leaf venation pattern.
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Unformatted text preview: A can always be identified from its leaves. Reproduction in Ginkgo is a dioecious tree. Both male and female "strobili" are reduced in number of and size of sporangia produced. The male "strobili" are formed from short pendant microsporophylls, each of which has microsporangia. The haploid microspores are retained within the sporangia and the male gametophyte consists of a pollen grain containing multiflagellated sperm. Mature pollen is ultimately released from the diploid sporangia. The female reproductive structure consists of 2 ovules (which is what the megasporangia are typically called in the seed plants) each of which contain archegonia. Pollen delivers the sperm to the female ovules, but sperm, once released from the pollen grain (the male or microgametophyte) must swim to the egg contained within the archegonium of the ovule....
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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