Sepals

A sepal is a leaf or petal-like blade in the flower of a vascular plant that encloses the petals and the remainder of the flower while it is budding. The sepals are the lowest parts of the flower organ; when the flower blooms, the sepals unfurl and flatten out beneath the rest of the flower.

Sepals are modified from leaves. They protect the terminal bud and the apical meristem inside while sexually reproductive organs develop in the bud.