appear as random mutations in several orchid species in nature and this is genetically controlled, although the expression can be influenced by both environmental changes and by stresses. The occurrence is unstable and the same plant may exhibit normally on the next flowering. In more highly evolved flowers such as orchids the details of pelorism may appear more complex with characteristics such as the two lateral petals replaced by two additional labella, the labellum replaced by an additional lateral petals in semipeloria or pseudopeloria where the modified labellum is less distinctively altered, however it is still distinguishable from the lateral petals and this confers a degree of zygomorphy upon the petal whorl. Although the production of peloric flowers has been shown to generally follow standard Mendelian inheritance, this is not fixed and had been linked to the inability of a plant to produce normal internodes, this failure resulting in the fusion of flower buds giving in actinomorphic flowers. Foxglove plants show the terminal peloric bud flowering first followed by the more normal buds flowering below, the reverse of the normal flowering pattern, the terminal flowers withering first. The CYCLOIDEA (CYC) gene controls floral symmetry and peloric antirrhinums have been artificially induced by this gene being knocking out. Etymology Peloria derives from both new Latin and from the Greek word , meaning 'monstrous'. Examples Pelorism is found in several orchid species, such as Phalaenopsis it is demonstrated by flowers with abnormal numbers of petals or lips as a genetic trait, the expression of which is environmentally influenced and may appear random. It is widely noted in the mint family and species such as Digitalis purpurea, gloxinia, Antirrhinum majus, Pelargonium, and auricula. Because peloric flowers are larger and arguably more attractive than normal flowers plants such as cultivars of the gloxinia (Sinningia speciosa) have been deliberately bred to have peloric flowers. See also Floral symmetry References External links Peloric Foxglove flowers Further reading Plant morphology