SeedPlants213-page12

SeedPlants213-page12 - The seed is surrounded by a bright...

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Seed-Dispersing Plants - 12 Pine Fraser Fir Juniper Reproduction in Conifers Conifers are generally monoecious and polycarpic (Male and female gametophytes are produced in separate strobili but both are on the same tree). The strobili are modified into cones. The cone scales are modified sporophylls (spore producing leaf) in the male, and more specialized, with a projection, called a ligule, subtending each cone scale in the female. In the female sporangia, the ovules (archegonia-containing structures) are typically borne on and protected by hardened cone scales. A bract subtends each cone scale. The female cone scales are not always hardened. In juniper, the cone is often called a juniper berry. Yews do not produce a hardened cone, either.
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Unformatted text preview: The seed is surrounded by a bright fleshy aril. The cone scales are spirally arranged along the megastrobilus forming the female cone. Yew with arils Mature pine cone True fir cones Each female cone scale has two ovules, or megasporangia. The ovule is a complex structure and is involved not just in meiosis to form the megaspores, but also in female gametophyte development and in seed development of the next generation. As in the other seed plants, the female gametophyte stage is totally dependent upon, and retained by, the sporophyte. Moreover, the next generation embryo sporophyte develops within the female gametophyte located in the previous generations sporophyte....
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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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