Sepal

A sepal is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom. The term sepalum was coined by Noël Martin Joseph de Necker in 1790, and derived from the Greek σκεπη (skepi), a covering.

Collectively the sepals are called the calyx (plural calyces), the outermost whorl of parts that form a flower. The word calyx was adopted from the Latin calyx, not to be confused with calix, a cup or goblet. Calyx derived from the Greek κάλυξ (kalyx), a bud, a calyx, a husk or wrapping, while calix derived from the Greek κυλιξ (kylix), a cup or goblet, and the words have been used interchangeably in botanical Latin.

Description

Sepals often appear similar to petals, and the difference between the two is often less clear in species of plants in which the sepals and petals have similar appearance to the point that they are termed tepals. This is particularly common in plants of the lily family such as the day lilies (genus Hemerocallis) and tulips (genus Tulipa).

Some flowers have no petals, and in these the sepals perform the functions of petals in attracting insects to the flower. The Wisteria flower is an example of such a flower. The sepal is a modified leaf that encloses the future petals, either individually or as a whole.

Morphology

In many plants, the sepals are the green parts of the flower that protect the bud before it opens. In some plants, they are hairy, rough, or spiky. In other plants, they can be smooth and shiny. Sepals are usually shorter than petals, but in some species, they grow large enough to be seen from above the flower.

Function

The function of the sepal is to protect the flower before it opens. The sepal covers the bud of the flower, protecting it from insects, wind, and other environmental conditions. Once the flower opens, the sepals often become less noticeable as they fold back against the stem of the plant.

See also

• Petal
• Flower
• Angiosperms
• Tepal
• Calyx (botany)

Sepal

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  Mature flower diagram
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  Petal sepal
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  Terengganu roselle
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  Vicia February 2008
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  Crataegus germanica