Rechinger, in his 1968 Flora Iranica account, considered Sterigmostemum to contain nine species in Iran. In 1980 Léonard excluded S. purpurascens from Sterigmostemum and transferred it to the new genus Petiniotia as P. purpurascens. Subsequently, in 1988 Jacquemoud retained this species in Sterigmostemum, but as subgenus Petiniotia. In 2000 Sonboli et al. excluded S. laevicaule from Sterigmostemum and considered it to be a synonym of Erysimum crassicaule. Phenetic analysis of morphological and anatomical characters from herbarium and fresh specimens supports the recognition of five species in Sterigmostemum (S. incanum, S. sulphureum, S. acanthocarpum, S. ramosissimum and S. longistylum). The results of cluster analysis and ordination based on these characters confirm Léonard's exclusion of S. purpurascens and transfer to the genus Petiniotia as P. purpurascens. A key is provided to distinguish Petiniotia from Sterigmostemum, followed by descriptions of the two genera and a conspectus of species.
