Listado florístico y aspectos ecológicos de la familia poaceae para Chihuahua, Durango y Zacatecas, México

We present a floristic checklist of the Poaceae in three north-central states of Mexico (Chihuahua, Durango and Zacatecas), results of investigations being carried out in the herbarium CIIDIR of IPN Durango, which allowed us to analyze some aspects of the richness of this family in the region. The floristic richness of the family Poaceae in Mexico is given by its geographical position in the contact area of the Holarctic and Neotropical regions, and for its rugged topography, climate and geology variables. Of the approximately 204 genera and 1182 species reported for Mexico, 117 genera (57%) and 505 species (43%) are distributed in this region of northern Mexico. We carried out an analysis of spatial distribution of the species and some ecological aspects that affects them. Habitat preferences indicate that 33.5% of the species found in temperate forest, 28.4% in grassland, 23.6% in desert scrub and 14.5 % in tropical deciduous forest, for its origin, it is found that 70% of the species are native to America, 20% are endemic to Mexico and 10% are exotic. The distribution of the subfamilies clearly response to their affinities, thus the Chloridoideae and Aristidoideae from tropical and subtropical more arid environments are the best represented in this region (42% and 5% respectively), followed in importance by the Panicoideae from tropical environments and austral distribution (28%), and the Pooideae from temperate environments and boreal distribution (22%). Results are discussed and other small groups with special substrate requirements.