The combinations Hibiscus moscheutos L. subsp. lasiocarpos (Cavanilles) O. J. Blanchard, H. clypeatus L. subsp. cryptocarpos (A. Richard) O. J. Blanchard, and H. clypeatus subsp. membranaceus (Cavanilles) O. J. Blanchard are validated for a central North American plant taxon, a Cuban plant taxon, and a Bahamian plant taxon, respectively. The name H. grandiflorus Michaux is lectotypified. A new name, Kosteletzkya semota O. J. Blanchard, is established for the West African K. stellata Hutchinson & Dalziel, a later homonym. The neotype of the Philippine endemic K. batacensis (Blanco) Fernández-Villar is changed. Two well-known species, K. virginica (L.) C. Presl ex A. Gray of eastern North America and K. pentacarpos (L.) Ledebour of Eurasia, are synonymized under the latter name.