Calyx

Calyx, the outer floral envelope or whorl of the perianth, which is generally green and often hairy externally, serving mainly a protective purpose. In other cases it is petaloid in texture and colour, as in Fuchsia, especially where the corolla is absent, as in Daphne, Clematis, Caltha, and Anemone. It then serves to attract insects to the flower. The hairs may serve to exclude crawling insects which might steal the nectar without effecting fertilisation. The leaves of the calyx, which are called sepals, have a broad base, simple outline, entire margin, and acute apex. They are usually three in number among Monocotyledons and five among Dicotyledons, and may be either distinct (polysepalous) or coherent from intercalary growth below them (gamosepalous). If not adherent to the ovary, the calyx is termed inferior; if adherent, superior. In symmetry it may be polysymmetric or monosymmetric, the most striking forms of the latter type being those that are spurred or calcarate, such as those of the larkspur, Tropaeolum, and Pelargonium. In duration the calyx may be caducous, as in poppies, falling as the flower opens; deciduous, as in the cherry, falling with the petals and stamens after fertilisation; or persistent, remaining in the fruit stage. In the latter case it may be either marcescent, or shrivelling, as in the gooseberry and medlar; or accrescent, growing larger around the fruit, as in the winter-cherry.