Calyx
All the sepals of one flower, taken together: the outer cup that protects the bud.
The calyx is the outermost ring of a flower. It encloses the bud and often stays on after the petals fall. On a carnation it is the firm green tube that holds the petals together, and when it splits the flower loses its shape, which growers count as a fault. In roselle, a kind of hibiscus, the fleshy red calyx is the part dried to make hibiscus tea. In Chinese lantern plants it swells into a papery orange case.