Objectives:

1- To identify and evaluate the vegetal communities at El Plomito, Sonora.

2- To evaluate in quantitative and qualitative ways the plant species found at El Plomito, Sonora.

3- To compare the vegetation between flats, hills and mountains at El Plomito, Sonora.

Vegetation was evaluated in qualitative and quantitative ways, and the similarities between flats, hills and mountains were evaluated, considering flora, soil, altitude, inclination degree, temperature and humidity. The linear interception method of Canfield was used, analyzing 46 transects of 100 square meters each.

For each vegetation type the species composition and structure were determined. Three different plant communities were found: Desertic microphyle bush, sarcocaulescent microphyle bush and high spinous bush. Sarcocaulescent microphyle bush is the most species-rich and the one with the most equitability of individuals for each species, whereas the Desertic microphyle bush shows the greatest dominance of species. The presence of such species like Oneya tesota (special protection, NOM-059, SEMARNAP 1997), Simmondsia chinensis and Carnegiea gigantea reinforce the importance to protect this area and to continue the efforts that may help to determine the actual status of its populations and the chances of its conservation and sustainable use.