Solanum allophyllum (Miers) Standl. and the Generic Delimitation of Cyphomandra and Solanum (Solanaceae)

Abstract

Solanum allophyllum has previously been placed in Cyphomandra and in Solanum. This species has a number of morphological features not found in Cyphomandra, but has been included in the genus because it has a similar growth habit, three-leaved sympodial units with inflorescences in branch forks, and tapered anthers with an abaxial thickening. When each of these characters is closely examined, however, important differences are found between the taxa, indicating that the features they share may not be structurally homologous. New evidence derived from crossing studies and cytological investigations also supports the exclusion of S. allophyllum from Cyphomandra. Solanum allophyllum is self-compatible, whereas all but the single domesticated species of Cyphomandra are self-incompatible, and the chromosomes of Cyphomandra are about 2.5 to 5.5 times larger than those of S. allophyllum. The anther morphology, self-compatibility, and small chromosomes are all consistent with placement of this species in Solanum.