Carpel

:Not to be confused with carpal, a wrist-bone.

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A carpel is the female reproductive organ of a flower; the basic unit of the gynoecium. The parts of the carpel are:

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• the stigma (plural: stigmas), usually the terminal (end) portion that has no epidermis and is fitted to receive pollen (male gametes); it is commonly somewhat glutinous or viscid;
• the style, a stalk connecting the stigma with the ovary below containing the transmitting tract, which facilitates the movement of the male gamete to the ovule; and
• the ovary (also also called a megasporophyll) containing the female reproductive cell or ovule.

The carpel (if single) or carpels (if fused) comprise the pistil of the flower. A flower with two or more fused carpels (called a compound ovary or compound pistil) is termed syncarpous. However, if the gynoecium consists of more than one distinct carpel, it will have more than one pistil and is then termed apocarpous. Apocarpous also pertains to any flower with a single carpel. Fertilization of the ovule or ovules results in development of the carpel(s) into a fruit.

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The gynoecium is the innermost whorl of the parts of a flower, and in many flowers the other parts (sepals, petals, and stamens) are attached to the receptacle beneath the gynoecium. In such cases, where the ovary lies above the attachments of the other distinct floral parts, the flower is described as hypogynous or as having a superior ovary. In some species (examples include plum, cherry, and blackberry), the other (noncarpellary) floral parts are fused to form a cup called a floral tube or calyx tube. In these flowers, the ovary lies physically lower than the lobes of the sepals and petals and below the point of attachment of the stamen filaments — the ovary is still considered to be superior but the flower is termed perigynous.

Related Topics:
Flower - Plum - Cherry - Blackberry

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In those flowers in which the floral tube is fused with the ovary, the sepals, petals, and stamens appear to grow out from the top of the ovary, and the flower is said to be epigynous and have an inferior ovary. Examples of plant families with inferior ovaries include orchid, sunflower, and cactus. The position of the ovary is an important consideration in the identification and classification of plant species, as well as the kind of fruit that develops after fertilization.

Related Topics:
Orchid - Sunflower - Cactus

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Carpel: Carpel anatomy ►