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Mature plant ovules
In seed plants , the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument , forming its outer layer, the nucellus or remnant of the megasporangium , and the female gametophyte formed from a haploid megaspore in its center. The female gametophyte — specifically termed a megagametophyte — is also called the embryo sac in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. In flowering plants , the ovule is located inside the portion of the flower called the gynoecium.
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Flowering Plant Reproduction II
This was investigated by studying the effect the position of an ovule within the pod has on seed abortion and seed production in Bauhinia ungulata. A GLM model was used to assess the effects of population, tree identity and ovule position within the pod on ovule fertilization, seed abortion, seed damage and seed maturation in two populations of B. However, seed survivorship was dependent on the position of the ovule within the pod; non-fertilized and early aborted ovules were found more often near the basal end of the ovary. The frequency of seed damage was not affected by position. Mature seeds were found mainly in the stylar half of fruits, where ovules are likely to be fertilized by fast pollen tubes.
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Ovule , plant structure that develops into a seed when fertilized. A mature ovule consists of a food tissue covered by one or two future seed coats, known as integuments. A small opening the micropyle in the integuments permits the pollen tube to enter and discharge its sperm nuclei into the embryo sac, a large oval cell in which fertilization and development occur.
Pollen grains from the greek palynos for dust or pollen contain the male gametophyte microgametophyte phase of the plant. Pollen grains are produced by meiosis of microspore mother cells that are located along the inner edge of the anther sacs microsporangia. The outer part of the pollen is the exine , which is composed of a complex polysaccharide, sporopollenin. Inside the pollen are two or, at most, three cells that comprise the male gametophyte. The tube cell also referred to as the tube nucleus develops into the pollen tube.