Abstract
The delimitation of Himatanthus (Apocynaceae) species has long been problematic, and much confusion remains as to which names and species delimitations should be adopted. In order to recognize and clarify the species of Himatanthus occurring in Peru, herbarium specimens were examined, coupled with detailed field observations. The present study recognizes three species in Peru: H. revolutus, H. tarapotensis and H. phagedaenicus. A key to identify the species, as well as descriptions, synonymy, specimens cited, and taxonomic comments are presented.