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The female cone (megastrobilus, seed cone, or ovulate cone) contains ovules which when fertilized by pollen become seeds. The female cone structure varies more markedly between the different conifer families and is often crucial for the identification of many species of conifers.
Pollen strobili of Pinophyta are similar to those of cycads (although much smaller) and Ginkgoes in that they are composed of microsporophylls with microsporangia on the abaxial surface. Seed cones of many conifers are compound strobili. The central stem produces bracts and in the axil of each bract is a cone scale. Morphologically the cone ...
The female cone then opens, releasing the seeds which grow to a young seedling. To fertilize the ovum, the male cone releases pollen that is carried in the wind to the female cone. This is pollination. (Male and female cones usually occur on the same plant.) The pollen fertilizes the female gamete (located in the female cone).
Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
In seed plants, the microgametophyte is called pollen. Seed plant microgametophytes consists of several (typically two to five) cells when the pollen grains exit the sporangium. The megagametophyte develops within the megaspore of extant seedless vascular plants and within the megasporangium in a cone or flower in seed plants.
The pollen is bisaccate. [1] The seed cones are highly modified with the few cone scales swelling and fusing at maturity. The cones are pedunculate and often solitary. The seed cone consists of two to five cone scales of which only the uppermost one or rarely two nearest the apex of the cone are fertile. Each fertile scale usually has one ...
The megaspores, in turn, develop into reduced female gametophytes that produce egg cells that, once fertilized, develop into seeds. Pollen cones or microstrobili usually develop toward the tips of the lower branches in clusters up to 50 or more.
Pinus albicaulis is the only type of tree on the summit of Pywiack Dome in Yosemite National Park. Pinus albicaulis, known by the common names whitebark pine, white bark pine, white pine, pitch pine, scrub pine, and creeping pine, [4] is a conifer tree native to the mountains of the western United States and Canada, specifically subalpine areas of the Sierra Nevada, Cascade Range, Pacific ...