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Peloria or a peloric flower is the aberration in which a plant that normally produces zygomorphic flowers produces actinomorphic flowers instead. This aberration can be developmental, or it can have a genetic basis: the CYCLOIDEA gene controls floral symmetry. Peloric Antirrhinum plants have been produced by knocking out this gene. [5]
Pelorism is the term, said to be first used by Charles Darwin, for the formation of 'peloric flowers' [1] which botanically is the abnormal production of radially symmetrical (actinomorphic) flowers in a species that usually produces bilaterally symmetrical (zygomorphic) flowers. [2] These flowers are spontaneous floral symmetry mutants.
The flowers called actinomorphics, radiate or polysymmetric have radial symmetry, as is the case of Tulipa gesneriana or Linum usitatissimum . In contrast, monosymmetrica l, dorsiventral or zygomorphic flowers have bilateral symmetry and the evolution of their shape is related to the need to attract and guide pollinators to them, as for example ...
In addition to animals, the flowers of some plants also show bilateral symmetry. Such plants are referred to as zygomorphic and include the orchid (Orchidaceae) and pea families, and most of the figwort family (Scrophulariaceae). [18] [19] The leaves of plants also commonly show approximate bilateral symmetry.
Actinomorphic – having a radial symmetry, as in regular flowers. Actinomorphy – when the flower parts are arranged with radial symmetry. Radial – symmetric when bisected through any angle (circular) Unisexual – Zygomorphic – one axis of symmetry running down the middle of the flower so the right and left halves reflect each other.
Animals mainly have bilateral or mirror symmetry, as do the leaves of plants and some flowers such as orchids. [30] Plants often have radial or rotational symmetry, as do many flowers and some groups of animals such as sea anemones. Fivefold symmetry is found in the echinoderms, the group that includes starfish, sea urchins, and sea lilies. [31]
This is an example of radial symmetry. When flowers are bisected and produce only one line that produces symmetrical halves, the flower is said to be irregular or zygomorphic. If, in rare cases, they have no symmetry at all they are called asymmetric. [23] [24]
[clarification needed] [example needed] [16] A disk flower (or disc flower) is a radially symmetric individual flower in the head, which is ringed by the ray flowers when both are present. [15] [16] In some species, ray flowers may be arranged around the disc in irregular symmetry, or with a weakly bilaterally symmetric arrangement. [15]