Sepal
One of the small, usually green leaf-like parts that wrap and protect a flower bud before it opens.
Sepals sit just below the petals. In bud they close over the flower like a case, keeping it from drying out or being eaten. When the flower opens they fold back, as on a rose, where the five green points under the bloom are the sepals. In some plants the sepals are the showy part: the blue or pink 'petals' of a hydrangea and the bright outer parts of a clematis are sepals. All the sepals of one flower together are called the calyx.