The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

. It is a structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepals when called a perigone. The term ''perianth'' is derived from Greek περί (, "around") and άνθος (, "flower"), while ''perigonium'' is derived from περί () and γόνος (, "seed, sex organs"). In the

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es and liverworts (

Marchantiophyta Liverworts are a group of non-vascular plant, non-vascular embryophyte, land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in wh ...

), the perianth is the sterile (neither male nor female) tubelike tissue that surrounds the female reproductive structure or developing

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

Flowering plants

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s, 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). When the perianth is in two whorls, it is described as biseriate. While the calyx may be green, known as sepaloid, it may also be brightly coloured, and is then described as petaloid. When the undifferentiated tepals resemble petals, they are also referred to as "petaloid", as in petaloid monocots or liliod monocots, orders of monocots with brightly coloured tepals. The corolla and petals have a role in attracting

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...

s, but this may be augmented by more specialised structures like the corona (see below). When the perianth consists of separate tepals the term apotepalous is used, or syntepalous if the tepals are fused to one another. The petals may be united to form a tubular corolla (gamopetalous or sympetalous). If either the petals or sepals are entirely absent, the perianth can be described as being monochlamydeous. 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

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. It is often positioned where the corolla lobes arise from the corolla tube. There can be more than one corona in a flower. The milkweeds ('' Asclepias'' spp.) have three very different coronas, which collectively form a flytrap pollination scheme. Some passionflowers ('' Passiflora'' spp.) have as many as eight coronas arranged in concentric whorls.Engler and Prantl Naturlichen Pflanzenfamilian Band 21 page 503 (figure 232b) The pappus of

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

, considered to be a modified calyx, is also called a corona if it is shaped like a crown.

References

Bibliography

External links

* {{botany Plant anatomy