There are two sepals which fall off before the petals expand.
The four sepals are arranged symmetrically, an outer median and an inner lateral pair.
From the upper rim of the receptacle are given off the five sepals, the five petals, and the very numerous stamens.
The sepals are generally organs for the protection of the flower-bud; the petals, for attracting insects by their conspicuous form and color; the foliage-leaves, for the assimilation of carbon dioxide and other associated functions.
There are five free sepals, overlapping in the bud, and, alternating with these, five free petals.