sepalen

Sepalen, in botany commonly referred to as sepals, are the outermost floral organs of a flower. They form the calyx, a protective envelope around the developing bud and, in many species, provide support for the petals once the flower opens. While sepals are often green and leaflike, they can be colored or showy in some plant families, contributing to the overall appearance of the flower.

Morphology and arrangement of sepals vary widely. In most dicots, there are multiple sepals arranged in a whorl that corresponds to the petals, though the exact number can differ among taxa. Sepals can be free (distinct) or fused, producing structures such as a calyx tube or cup. They may persist after flowering and contribute to the fruit or seed dispersal, or they may wither early and fall away. In many plants, sepals are small and inconspicuous; in others they are larger and more noticeable.

Variation and terminology are influenced by evolutionary patterns. Some plants possess an epicalyx, a secondary whorl of bracts external to the calyx, as seen in hibiscus and related groups. In monocots, sepals and petals are often difficult to distinguish, and the term tepals is used when the perianth parts are indistinguishable in color or form.

Examples illustrate diversity in sepals. Roses typically have five sepals that are green and somewhat persistent; lilies have a perianth with six tepals (often difficult to separate into petals and sepals); orchids commonly show three outer tepals; magnolias may have numerous, petaloid perianth parts. Sepalen play a key role in flower morphology and are useful in taxonomic classification.