Perianth

The term perianth has two similar but separate meanings in botany:

Diagram showing the parts of a mature flower; here the perianth is separated into sepals and petals

• In flowering plants, the perianth are the outer, sterile whorls of a flower. The perianth may either consist of the calyx (all sepals) and the corolla (all petals), or, if sepals and petals are not differentiated, of the perigone (all tepals]).
• In liverworts (Marchantiophyta), the perianth is the sterile tubelike tissue that surrounds the female reproductive structure (or developing sporophyte).