Perianth

In the mosses and liverworts (Marchantiophyta), the perianth is the sterile tubelike tissue that surrounds the female reproductive structure (or developing sporophyte).

In flowering plants, the perianth may be described as being either dichlamydeous/heterochlamydeous in which the calyx and corolla are clearly separate, or homochlamydeous, in which they are indistinguishable (and the sepals and petals are collectively referred to as tepals).

The corolla and petals have a role in attracting pollinators, but this may be augmented by more specialised structures like the corona (see below).

In some taxa, for instance some magnolias and water lilies, the perianth is arranged in a spiral on nodes, rather than whorls.

An additional structure in some plants (e.g. Narcissus, Passiflora (passion flower), some Hippeastrum, Liliaceae) is the corona (paraperigonium, paraperigon, or paracorolla), a ring or set of appendages of adaxial tissue arising from the corolla or the outer edge of the stamens.