Monarda subgenus Cheilyctis (Lamiaceae) is a monophyletic group comprised of 16 species of annual and perennial herbs, subshrubs, and shrubs. It has a temperate North American distribution that extends from southern Canada, across much of the United States, into Mexico as far south as Michoacán. The group is most easily characterized by strongly arching upper corolla lips, inserted stamens, and verticillate glomerules. A multivariate morphometric analysis was performed to assess species circumscriptions. Fifty morphological characters were measured from 386 herbarium specimens. Gower's similarity coefficient was used to perform unweighted pair-group method using arithmetic averages (UPGMA) and principal coordinates analysis (PCOA). The results revealed 11 distinct clusters that correspond to previously accepted species (M. austromontana, M. citriodora, M. clinopodioides, M. fruticulosa, M. humilis, M. maritima, M. mexicana, M. pectinata, M. punctata, M. stanfieldii, and M. viridissima) and five clusters that represent new species or combinations (see below). Boxplots of the data elucidate the characters important to the circumscription of the species. A monograph of this group, including a morphological cladistic analysis, is also presented. Sections covering taxonomic history, morphology, phylogeny, and taxonomy, as well as a key to the species of the subgenus are provided. In addition to a full synonymy and description, phenology, distribution, a specimen image, and a list of representative specimens is also provided for each species. Two species are described (Monarda n. sp. 1, Monarda n. sp. 2), and three new combinations are proposed (M. arkansana ined., M. occidentalis ined., M. villicaulis, ined.)
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