Noun
The leaves of a flower generally, especially when the calyx and corolla are not readily distinguished.
A saclike involucre which incloses the young fruit in most hepatic mosses. See Illust. of Hepatica.
Source: Webster's dictionaryThe immature seeds are infested and desapped by larvae staying in the portion covered by the perianth of the immature seed; the seeds then drop off or survive deformed. Source: Internet
The style is much longer than the perianth, and is initially trapped by the upper perianth parts. Source: Internet
When the styles and perianth parts are different colours, the visual effect is of a colour change sweeping along the spike. Source: Internet