A mature flower. In this example the perianth is separated into a calyx (sepals) and corolla (petals)
The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower. It forms an envelope surrounding the sexual organs. 
It includes the calyx (sepals) and the corolla (petals) when called a perigone.
The term perianth is got from the Greek περί (peri, "around") and άνθος (anthos, "flower"). Perigonium is got from περί (peri) and γόνος (gonos, "seed, sex organs").
In the mosses and liverworts (Marchantiophyta), the perianth is the sterile tubelike tissue that surrounds the female reproductive structure (or developing sporophyte).
- ↑ Beentje H. & Williamson J. 2010. The Kew Plant Glossary: an illustrated dictionary of plant terms. Royal Botanic Gardens, Kew: Kew Publishing.