Homeosis, the expression of features characteristic of one structure in the position of a different structure, and its role in floral development and evolution is explored in several different species of angiosperms. The expression of perianth features in stamen positions, and of inflorescence features within the flower is demonstrated in a comparative study of single- and double-flowering begonias. Floral development in three native plant species is then described, and compared to published accounts of development and phylogeny in related species to show: the expression of petal features in stamen positions in Sanguinaria canadensis; the replacement of petals with stamens and vice versa within and among plants of Actaea rubra; and the replacement of stamens with tepals in Calla palustris. These three species are all examples of naturally occurring homeosis, suggesting an important role for homeosis as an evolutionary process.

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