It chief character that distinguishes "Pachypodium bicolor" from other species with yellow corolla is the presence of a white corolla tube or throat to the flower. "Pachypodium bicolor" is part of the "Pachypodium rosulatum" complex, where discussion centers on rather one is dealing with one species with many varieties, as Gordon Rowley argues, or many separate distinct species. The corolla, the collective term for the petals of a flower or the inner whorl of the perianth, in the nexus for taxonomical confusion of the taxon.