What is the structure of the perianth?

The perianth of a flower is a leaf-like organ that comes from the leaves. It is an amalgamation of sepals with petals. Tiny green leaves are combined into a cup. She is the outer circle of the perianth.
And the inside is called a whisk. Corolla consists of large bright petals.
The structure of the perianth is double (calyx with a corolla), as well as simple (sepals do not differ from petals or petals are absent). A simple perianth occurs: corolla and calyx.