kelkblad

Kelkblad is a term used in Dutch botany to denote the leaf-like structures that form the calyx of a flower, i.e., the sepals. The word combines kelk (calyx) and blad (leaf). In many flowering plants, the kelkblad serves to protect the developing floral bud and is part of the outer whorl beneath the petals.

Kelkbladen are typically arranged in a whorl and surround the developing flower. The number and shape of sepals vary widely among plant groups, with common configurations of four or five, though exceptions exist. They are usually green and leaf-like, but in some species they may be colored or show petaloidy, resembling petals. The sepals may persist after flowering or fall away as the flower opens.

Functionally, the kelkblad protects the bud during development, provides support as the blossom enlarges, and can contribute to photosynthesis in many species. After pollination or fruit set, sepals can wither or persist as part of the fruit-bearing structure, depending on the plant.

In taxonomy and terminology, kelkblad is synonymous with the calyx or with sepals, the outermost part of the perianth. Variation in kelkblad size, number, and morphology is commonly used as a diagnostic character in plant identification and classification. See also calyx, sepal, perianth.