The sepal is a part of the flower that encloses and protects the developing reproductive structures. Sepals are considered part of the flower and are the structure that covers a flower bud, protecting it as it develops. They are the outermost layer of a flower, which encloses the flower bud and is collectively called the calyx. Sepals are small, leaf-shaped, green-colored, and the vegetative part of a plant found only in flowering plants. They are the vegetative part of a flower, which functions by protecting the rising buds and by supporting the petals when in bloom. Sepals mainly consist of parenchyma, secretory cells called laticifers, tannin cells, and other specialized plant cell organelles. The primary functions of sepals are to provide support to the flowers, prevent the flower from drying out, and protect the reproductive organs within the flower. In some plants with no petals, sepals function as petals. Sepals also safeguard the bud and flowers from harsh environmental conditions. They protect both flowers and fruits by producing chemicals that would ward off predators. In some rare plant species, sepals serve as thorns and function by protecting the flower. They form a protective cover for a flower at its bud stage as they cover around it until they are ready to bloom.