Taxonomic revision and distribution analysis of Hedeoma (Lamiaceae) in Mexico

Hedeoma is one of the five most species-rich genera of Lamiaceae in Mexico. It is also significant because several species are used for tea or as condiments. Some new species have been described after the most recent taxonomic treatment of the genus, there are ambiguities in morphological circumscription manifested in recurrent misidentified specimens in herbaria, the distribution was not thoroughly evaluated in previous publications, and there are no conservation status assessments. Hence, the present study seeks to update morphological descriptions under a parallel structure and analyse species richness distribution. Morphological analyses support the transfer of H. oblongifolia, H. rzedowskii and H. tenuipes into synonymy, reducing the number of species in Mexico to 26. The Chihuahuan Desert, Sierra Madre Occidental and Sierra Madre Oriental are the biogeographic provinces with the most species of Hedeoma, particularly an area between the states of Coahuila, Nuevo León, San Luis Potosí and Zacatecas. The conservation status of five species was determined as Critically Endangered, six as Endangered, three as Vulnerable and the rest as Least Concern according to IUCN categories and criteria. The distribution of the species richness of Hedeoma emphasizes the need to pay more attention to the conservation of arid and semiarid areas in the country. Citation: Velázquez-Ríos P., González-Gallegos J. G. & García-Peña M. del R. 2026: Taxonomic revision and distribution analysis of Hedeoma (Lamiaceae) in Mexico. – Willdenowia 56: 63–127. Version of record first published online on 17 February 2026.