The sequence of the intron within the chalcone synthase A gene (ChsA) was used to characterize Petunia integrifolia subsp. integrifolia var. depauperata (Fries) Smith et Downs, P. altiplana Ando et Hashimoto, P. littoralis Smith et Downs, and an unknown taxon from the town of Torres in Brazil. Based upon the intron, the Torres taxon most closely resembled P. integrifolia. The unrooted phylogenetic tree suggested that P. integrifolia was more closely related to P. littoralis than P. altiplana.