We thank the curators of the following herbaria for making their specimens available for this study: ASU, CAUP, COL, CUVC, HUA, MO, PSO, QCNE. M. L. Kawasaki and an anonymous reviewer kindly offered many helpful suggestions that improved this paper. We are grateful to Bobbi Angell for preparing the illustration. Carlos Parra-O. is grateful to Herbario Nacional Colombiano (COL) - Instituto de Ciencias Naturales - Universidad Nacional de Colombia for its support.