pistil (pĭsˈtĭl) [key], one of the four basic parts of a flower, the central structure around which are arranged the stamens, the petals, and the sepals. The pistil is usually called the female reproductive organ of a flowering plant, although the actual reproductive structures are microscopic. The pistil has a bulbous base (the ovary) containing the ovules, which develop into seeds after fertilization of egg cell(s) in the ovule. A pistil is composed of one or more highly modified leaves (carpels), each containing one or more ovules. A flower may have one or more simple pistils, each a separate organ, or, in higher orders, a compound pistil, formed of several fused carpels. Usually, there is above the ovary a stalk (the style) bearing on its tip the stigma, where the pollen grains land and germinate (see pollination). The stigma is often sticky or hairy, to retain the pollen. Evolutionary relationships can often be inferred from the location of the ovary in relation to the other parts of the flower. If the stamens, petals, and sepals are attached beneath the ovary, the flower is hypogynous and the ovary is superior; if they are attached above, the ovary is inferior and the flower epigynous; if the ovary is located in a receptacle at the outer edges of which are attached the other flower parts, it is called superior or half-inferior and the flower perigynous. A flower that has one or more pistils but no stamens (or nonfunctional ones) is called pistillate, or female, as distinguished from a staminate, or male, flower, in which the pistil is nonfunctional or absent.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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