Perianth

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Diagram showing the parts of a mature flower. In this example the Perianth is separated into a Calyx (sepals) and Corolla (petals)

The perianth (sometimes called perigonium or perigon) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs. The term perianth is derived from the Greek peri, meaning around, and anthos, meaning flower, while perigonium is derived from gonos, meaning seed, i.e sexual organs.

Flowering plants[edit]

In flowering plants, the perianth consists of the calyx, consisting of sepals and the corolla consisting of petals. These may be described as being either dichlamydeous in which the two components are clearly separate, or homochlamydeous, in which they are indistinguishable. In this case the perianth is described as a Perigonium (perigon), and the sepals and petals are collectivley referred to as tepals. When the perianth is in two whorls, it is described as biseriate. While the calyx may be green, it may also be brightly coloured, and is then described as petaloid. The corolla and petals have role in attracting pollinators, but this may be augmented by more specilised structures like the corona (see below).

When the corolla consists of separate petals the term apotepalous is used, or polypetalous where there are many petals. In contrast the petals may be united to form a tubular corolla (gamopetalous or sympetalous).


Types of perianth
Achlamydeous (absent perianth) 
Monochlamydeous or Haplochlamydeous (Corolla, but no Calyx) 
Monochlamydeous (Calyx, but no Corolla), or Homochlamydeous (undifferentiated) 
Heterochlamideous or Dichlamydeous (separate Calyx and Corolla) 

Both sepals and petals may have stomata and veins, even if vestigial. In some taxa, for instance some Magnolias and water lilies the perianth is arranged in a spiral on nodes, rather than whorls. Flowers with spiral perianths tend to also be those with undifferentiated perianths.

Corona[edit]

Flower of Narcissus showing an outer white corolla with a central yellow corona (paraperigonium)
Flower of Passiflora incarnata showing corona of fine appendages between petals and stamens

An additional structure in some plants (e.g. Narcissus, Passiflora (Passion flower), some Hippeastrum, Liliaceae) is the Corona (Paraperigonium, or Paraperigon), a ring of adaxial tissue arising from the corolla, perianth or filaments. This may consist of separate appendages, or be united. Strap shaped Ligules, as in Asteraceae are an example.

Ligulate floret, typical for flowers of some members of the family Asteraceae:
A. ovary
B. pappus
C. theca
D. ligule
E. style with stamen

Liverworts[edit]

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

Bibliography[edit]

External links[edit]

  • The dictionary definition of perianth at Wiktionary