Pelorism is the term, said to be first used by Charles Darwin, for the formation of 'peloric flowers' which botanically is the abnormal production of radially symmetrical (actinomorphic) flowers in a species that usually produces bilaterally symmetrical (zygomorphic) flowers. These flowers are spontaneous floral symmetry mutants. The term epanody is also applied to this phenomenon. Bilaterally symmetrical (zygomorphic) flowers are known to have evolved several times from radially symmetrical (actinomorphic) flowers, these changes being linked to increasing specialisation in pollinators. History Pelorism has been of interest since a five-spurred variety of the common toad-flax (Linaria vulgaris L.) was first discovered in 1742 by a young Uppsala botanist on an island in the Stockholm archipelago and then in 1744 described by Carl Linnaeus. The mutant, spreading vegetatively, had five spurs rather than the usual one; however, the rest of the plant was normal. Linnaeus found that this variety was contrary to his concept that genera and species had universally arisen through an act of "original creation and remained unchanged since then". Linnaeus called this type of mutant a 'Peloria', the Greek for 'monster' or 'prodigy', because of the huge implications for the then current belief that species were immutable. He wrote that "This is certainly no less remarkable than if a cow were to give birth to a calf with a wolf's head." The peloric plant fascinated Linnaeus to the extent that he grew it at his summer residence in Hammarby and his explanation for it was that a toad-flax had been pollinated by another species. Charles Darwin, Charles Victor Naudin, Johann Wolfgang von Goethe and Hugo de Vries amongst others analysed and wrote about this significant mutation. The botanist Thomas Fairchild corresponded with Carl Linnæus. Fairchild scientifically produced an artificial hybrid, Dianthus caryophyllus x barbatus in 1717 that became known as 'Fairchild's Mule', a cross between a Sweet william and a Carnation pink. The production of hybrids further undermined the belief that species as created by God were immutable. Appearance and causation It is notable in foxgloves that the terminal flower more frequently develops peloric features than lateral flowers and this has had been put down to terminal buds having a greater supply of sap. Charles Darwin took a particular interest in peloric flowers, growing and cross-pollinating antirrhinums himself, as he saw the phenomenon as suggestive of a partial reversion to a past or ancestral type. Peloric forms quite commonly