kelkbladen

Kelkbladen, in English sepals, are the outermost organs of a flower and form the calyx. They enclose and protect the developing bud and usually lie beneath the petals. In many plants the sepals are green and leaf-like, but in some species they can be colored or petaloid, contributing to the flower’s appearance.

Kelkbladen can be free (polysepalous), with distinct sepals, or fused at the base to form a calyx tube (gamosepalous). The number of sepals often corresponds to the number of petals, commonly three or five, though there is variation among plant families. After flowering, sepals may persist around the fruit and help protect it, or they may wither and fall away.

The primary functions of kelkbladen are to protect the flower in bud and to support the floral organs as the flower opens. In species with petaloid sepals, the sepals can contribute to attracting pollinators, but in many flowers petals provide most of the showy color and scent. Sepals can also be involved in photosynthesis in some early-diverging angiosperms where they remain green.

In taxonomy and morphology, kelkbladen are distinguished from petals by their position, structure, and often their color. When sepals and petals are similar in appearance, the terms tepals are used. The study of sepal number, fusion, and persistence provides useful characters for identifying plant groups and understanding floral evolution.