Peloria

Peloria is a botanical term describing an abnormal or derived condition in which a normally bilaterally symmetrical (zygomorphic) flower becomes radially symmetrical (actinomorphic). The phenomenon, also called pelorism, can appear spontaneously in wild populations, arise under cultivation, or be induced experimentally, and has been documented in a range of angiosperm lineages.

The word peloria derives from Greek roots meaning "monstrous" or "marvelous" and has been used in botanical literature since the 18th and 19th centuries. Charles Darwin discussed peloric flowers in relation to variation and heredity, using them as examples of how single changes in development can alter complex structures.

Genetic and developmental studies have linked pelorism to changes in the expression or function of genes that establish floral dorsoventral (front–back) identity. In several taxa, mutations affecting members of the TCP family (for example CYCLOIDEA in Antirrhinum) or interacting transcription factors can disrupt asymmetric patterns and yield radialized corollas. Other gene families, including MADS-box regulators, also participate in the wider program that can be modified to produce peloric forms.

Ecologically, peloric flowers may alter pollinator interactions by reducing specialized floral cues, sometimes decreasing reproductive success but occasionally broadening pollinator visitation. Peloria remains of interest in evolutionary developmental biology and horticulture as a visible example of how developmental genetic changes produce morphological novelty.