Vegetative and Trichome Morphology Distinguish the Monardella ovata Species Complex from the Monardella odoratissima Species Complex: Taxonomic Studies in Monardella (Lamiaceae) VII

Abstract Monardella (Lamiaceae) is a taxonomically complex western North American genus ranging from the Pacific coast to the western slopes of the Rocky Mountains and from southern British Columbia in Canada to the Cape region of Baja California Sur in Mexico. We applied a combination of gross vegetative morphology, trichome morphology and abundance/distribution, and molecular data to clarify taxonomic discontinuities, specifically regarding the monophyly of plants formerly treated within Monardella odoratissima. The data suggest a clear distinction between the non-monophyletic M. odoratissima species complex and the M. ovata species complex, thus resolving taxonomic ambiguities within and between them. We formally recognize plants from southern Oregon, northern California, and western Nevada previously misapplied to M. odoratissima as belonging to the M. ovata species complex. We introduce the following taxonomic and nomenclatural revisions: describe M. ovata Greene subsp. lenmaniae as a novel subspecies; present M. ovata subsp. pallida at a new position and rank; recognize M. modocensis, M. ovata, and M. rubella as accepted taxa; designate lectotypes for M. modocensis and M. rubella; and designate M. californica and M. tortifolia as new synonyms under M. ovata.