H. S. Irwin and R. C. Barneby made a significant contribution to the knowledge of Leguminosae, especially in the tribe Cassieae (Caesalpinioideae). Nevertheless, their work included use of some unconventional terms for type designations, i.e., lectoholotypus and neoholotypus, which do not appear in the International Code of Nomenclature for algae, fungi, and plants. Some authors have recognized them as lectotypes, and we interpret them as such. Analyzing the 53 names for which a “neoholotypus” was designated, we identified several other errors by Irwin and Barneby. These include citation of incorrect type collection numbers for Cassia atroglandulosa Taub. ex Harms and C. laxiracemosa Harms and of an incorrect herbarium acronym for C. catingae Harms and C. sincorana Harms. Here, we provide brief explanations to clarify these situations. A second-step lectotype is designated for C. repens Vogel. Finally, it is noted that the type designation of C. bradei Ekman ex Harms requires, at least, second-step lectotypification, which cannot be done until the herbarium at S becomes accessible.