Lycianthes tricolor was first described (in Solanum) in 1813, based on a painting from the Sessé and Mociño expedition to New Spain. In 1904, the similar L. arrazolensis was described (also in Solanum), and since that time, plant collectors have had difficulty separating L. tricolor from L. arrazolensis. Since then four more species allied to L. tricolor and L. arrazolensis have been described: L. surotatensis in 1948, L. jalicensis in 1998, and more recently L. venturana and L. michaelneei in 2014. This article provides a key to separate the six species included in series Tricolores, with updated species descriptions, synonymy, typification, distribution, and illustrations of characteristics (i.e. stamens, seeds, calyces). We include discussion of specimens that belong in series Tricolores, but are difficult to place and require additional study, as well as the uncertain status of L. arrazolensis var. patentipila.