Disc flowers of Helianthus petiolaris (Asteraceae) are usually purple red due to anthocyanin pigments in corolla lobes, style and stigma. However, yel low-flowered plants are occasionally found. The inheritance of this trait was studied through crosses between different phenotypes and the results indi cated that flower color is controlled by two genes with complementary action, both loci being dominant and independently inherited. This agrees with results obtained in cultivated sunflower, H. annuus, where one to three dominant genes have been proposed for anthocyanin expression in different organs.