Sepal

Tetramerous flower of Ludwigia octovalvis showing petals and sepals.

A sepal (from Latin separatus "separate" + petalum "petal") is a part of the flower of angiosperms (flowering plants). Sepals in most flowers are green and lie under the more conspicuous petals. However, the term tepal is usually applied when the petals and sepals share the same color, or the petals are absent and the sepals are colorful. When the flower is in bud, the sepals enclose and protect the more delicate floral parts within. Morphologically they are modified leaves. The calyx (the sepals) and the corolla (the petals) are the outer sterile whorls of the flower, which together form what is known as the perianth.[1]

The number of sepals in a flower is its merosity. Flower merosity is indicative of a plant's classification. The merosity of a eudicot flower is typically four or five. The merosity of a monocot or palaeodicot flower is three, or a multiple of three.

The form of the sepals vary considerably among the flowering plants. Often, the sepals are much reduced, appearing somewhat awn-like, or as scales, teeth, or ridges. Examples of flowers with much reduced perianths are found among the grasses. In some flowers, the sepals are fused towards the base, forming a calyx tube (as in the Lythraceae family),[2] a floral tube that can include the petals and the attachment point of the stamens.

References

  1. ↑ Davis, P.H.; Cullen, J. (1979). The identification of flowering plant families, including a key to those native and cultivated in north temperate regions. Cambridge: Cambridge University Press. pp. 106. ISBN 0521293596. 
  2. ↑ Carr, Gerald. "Lythraceae". University of Hawaii. http://www.botany.hawaii.edu/FACULTY/CARR/lythr.htm. Retrieved 2008-12-20. 

See also