Flora and Vegetation Associated with Dichromanthus cinnabarinus (La Llave & Lex.) Garay (Orchidaceae, Spiranthinae) in Northeastern Mexico

Studies conducted in northeastern Mexico have not provided information on the flora and vegetation associated with Dichromanthus cinnabarinus. Therefore, it is necessary to study the areas where this orchid is distributed to understand the plant vegetation interaction. Research questions: What plant species are associated with Dichromanthus cinnabarinus? What is the degree of similarity among the plant communities with which Dichromanthus cinnabarinus is associated? Study site: Northeastern Mexico, comprehending the states of Coahuila, Nuevo Leon and Tamaulipas. Methods: The study sites were selected consider-ing the presence of Dichromanthus cinnabarinus. Regarding the study of the plant struc-ture, the tree, shrub, and herbaceous strata were obtained by the methodology of quad-rants. Data were collected in April and August 2017. The results were analyzed using the Importance Value Index (IVI) for each stratum present and a Parsimony Analysis of En-demicity (PAE) for the plant communities. Results: In the study area, a total of 33 families, 60 genera and 69 species were registered. The representative families are Asteraceae with eight species, Asparagaceae with six, Fabaceae with five, followed by Cactaceae, Poaceae and Roasaceae with four species each. Regarding endemic species, a total of 11 species distributed in nine genera were registered in the study sites. Conclusions: In northeastern Mexico, Dichromanthus cinnabarinus is found associated with Aristida adscensionis L., Agave lechuguilla Torr. Bouteloua sp., Euphorbia antisyphilitica Zucc., Agave striata var. striata (Salm-Dyck) and Rhus virens Lindh. ex A. Gray. Moreover, Dichromanthus cin-nabarinus is observed in some sites with contrasting flora, according to the resulting list of endemic species. It is important to establish priority areas for wildlife conservation in northeastern Mexico.