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Petals are usually surrounded by an outer whorl of modified leaves called sepals, that collectively form the calyx and lie just beneath the corolla. The calyx and the corolla together make up the perianth, the non-reproductive portion of a flower. When the petals and sepals of a flower are difficult to distinguish, they are collectively called ...
The calyx (the sepals) and the corolla (the petals) are the outer sterile whorls of the flower, which together form the perianth. [17] In some plants, such as Aristolochia , the calyx is the primary whorl, forming a flower up to 20 inches (51 cm) wide, with one sepal growing to a length of 13 feet (4.0 m) – Aristolochia grandiflora , the ...
The term was first proposed by Augustin Pyramus de Candolle in 1827 and was constructed by analogy with the terms "petal" and "sepal". [ 1 ] [ 2 ] (De Candolle used the term perigonium or perigone for the tepals collectively; today, this term is used as a synonym for perianth .) [ 3 ]
Slightly united to an organ of another kind, [13] usually to a part of another whorl, e.g. a sepal connected to a petal. Contrast adnate. adnate Grown from or closely fused to an organ of a different kind, [13] especially along a margin, e.g. a stamen fused to a petal.
In some families, such as the grasses, the petals are greatly reduced; in many species, the sepals are colorful and petal-like. Other flowers have modified petal-like stamens; the double flowers of peonies and roses are mostly petaloid stamens. [22] Many flowers have symmetry.
The ABC model states that the identity of these organs is determined by the homeotic genes A, A+B, B+C and C, respectively. In contrast with the sepal and petal verticils of the eudicots, the perigone of many plants of the family Liliaceae have two nearly identical external petaloid verticils (the tepals).
A mature flower. In this example, the perianth is separated into a calyx (sepals) and corolla (petals) The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepals when called a perigone.
Most flowers are large and colourful, except for Medeoleae. Both the petals and sepals are usually similar and appear as two concentric groups (whorls) of 'petals', that are often striped or multi-coloured, and produce nectar at their bases. The stamens are usually in two groups of three (trimerous) and the pollen has a single groove (monosulcate).