Abstract
Banisteriopsis includes species that are difficult to define, and there is a hypothesis that sympatric species are more similar than those with wide distributions. The objective of this study was to test the circumscription of species related to B. malifolia to examine the relationship between geographical distribution, sympatry, and allopatry with the morphological variation of taxa, as well as to assess the degree of threat to the taxa. The results surprisingly point to greater morphological variation in allopatric species than in sympatric ones, the taxa are better explained within the current circumscription and no corroborate the new status for Banisteriopsis malifolia var, appressa recently proposed. We confirm the dramatic occurrence of threatened species in this group.