LAUSR

Background and Aims: The genus Stevia (Eupatorieae) is the third most diverse of the family Asteraceae in Mexico, with 116 species, of which 107 are endemic to the country. Its species are characterized by a cylindrical, uniseriate involucre, consisting of five bracts surrounding five flowers and cylindrical to fusiform achenes, usually with a pappus of scales, scales and awns or coroniform. Even though it is relatively simple to recognize the genus Stevia , the identification of its species is often quite complicated, as many species are not clearly delimitated, and in addition many hybridize or form apomictic populations. Hence, as a first strategy to improve the knowledge of the genus Stevia in Mexico, a taxonomic synopsis of the genus was carried out in the state of Morelos, which includes one fifth of the Mexican species. Methods: The specimens of the National Herbarium of Mexico (MEXU), as well as specimens from other national and foreign herbaria were studied in detail. Based on examination of the specimens the descriptions and key were prepared, and from the collection labels the ecogeographical data of the species were synthesized. The locations were georeferenced to elaborate the distribution maps. Key results: A synopsis of the genus for Morelos is presented, which includes a key for the identification of the species, descriptions of each of them and maps illustrating their geographical distribution in the state. Conclusions: In the state of Morelos, there are 25 species of the genus, 17 of them endemic to Mexico. The species grow preferentially in the temperate forests of the state, especially in the pine-oak and oak forests, with a few of them tolerating the tropical lowland environments.