Solanum sect. Anarrhichomenum is a subclade of viny, non-tuber bearing, node-rooting plants of the potato clade, consisting of both South and Central American species groups. Within the potato clade, most systematic attention has been focused on relatives of the cultivated potato and tomato, while other more inconspicuous groups, like Solanum sect. Anarrhichomenum, remain particularly understudied. This study presents part of an ongoing effort to revise the Mesoamerican species of Solanum sect. Anarrhichomenum by determining species-limits from morphometric, palynologyical, and molecular data. Morphometric analyses were conducted on a sample of 73 variables measured from 175 herbarium specimens representing all known species of Mesoamerican Solanum sect. Anarrhichomenum (S. appendiculatum, S. skutchii, S. subvelutinum, S. tacanense, S. ionidium and the new species currently in manuscript, S. tavinuuyuku). These data were then explored using FAMD and multivariate statistical analyses, which revealed a series of taxonomically informative morphological characters separating species and aided in the initial discovery of S. tavinuuyuku, the first new species to be added to Mesoamerican Solanum sect. Anarrhichomenum in over 70 years. To better understand the reproductive biology of the members of this group, morphological investigations were followed up by examination of pollen grains. Flowers of S. appendiculatum, the only known dioecious species in the potato clade, are hermaphroditic but distylous, as are all members of the S. appendiculatum species group. Previous work found that pollen produced by anthers of long-styled plants of S. appendiculatum were inaperturate and non-functional. Similarly, we looked at pollen grains from long and short-styled flowers in other members of the S. appendiculatum species group, using phase contrast microscopy, to determine whether dioecy exists throughout the group. Inaperturate and tricolporate pollen were discovered in long-styled and short-styled flowers, respectively, of all species in this study and suggests that all Mesoamerican members of Solanum sect. Anarrhichomenum are dioecious.