The Dioscoreaceae are widely distributed in the tropics, but despite the diversity and utility of the taxa of this family as food (e.g. yam) they are often poorly delimited morphologically and have complicated taxonomic issues. The Dioscorea campestris assemblage comprises 11 names in the literature, with considerable morphological variation among herbarium specimens. Macro- and micro-morphological examinations of the tubers, stems, and pollen indicated the recognition only of D. campestris and the proposal of a new combination— Dioscorea pedalis; the other nine names are reduced to synonyms of D. campestris. We report here the pollinic, anatomical, and morphological characters of D. campestris and D. pedalis, and describe the ecology, phenology, geographical distributions, etymology, conservation status, and taxonomies of both species.