Dichotomous key to the species of Solanum (Solanaceae) in Mexico

Abstract

Background: The genus Solanum (Solanaceae) groups annual, perennial and epiphytic herbs, herbaceous and woody lianas, shrubs and suffrutex, and trees. The flowers are pentamerous, gamosepalous and gamopetalous, with stellate, pentagonal or rotate corollas. The anthers dehisce by apical pores and the fruit is a berry. Among angiosperms, Solanum is a mega-diverse group, ranked among the 10 most diverse genera. The group includes 1,234 species but the infrageneric limits and relationships are still debated. Mexico is a center of diversification of the genus, but morphological variation and the numerous names published, difficult the species identification.

Questions: How many species of Solanum are there in Mexico? What morphological characters are important for their identification?

Studied taxon: Solanum

Study site: Mexico

Methods: We reviewed herbarium specimens deposited at 15 herbaria and 10 digital collections and databases. We validated the names on Tropicos, The Plant List, the International Plant Names Index and the Solanaceae Source. We also gather the protologues and printed out the nomenclatural types deposited at Global Plants. Lastly, we observed vegetative and floral variation and distribution range of the species to construct the dichotomous keys.

Results: There are 134 species of Solanum, grouped into 22 sections. We presented keys for sections within Solanum and species within each section. Additionally, we showed photographs of representative species.

Conclusions: Mexico is a diversification center for Solanum, the group is also a good proxy of the Mexican angiosperm flora. Dichotomous keys will facilitate the identification in the field and herbaria.