Research in the Sierra Madre Occidental of Eastern Sonora, MexicoThe Flora of Yécora Thomas R. Van Devender and Ana L. Reina G.
In 1673 the Jesuit missionary Alonso Victoria founded the settlement of San Idelfonso de Yécora in eastern Sonora. In 1916, it was designated as the seat of the Municipio (= County) de Yécora by Governor Adolfo de la Huerta. It is located at an elevation of 1550 m in a grassland valley surrounded by pine-oak forest slopes. The Municipio has an area of 3312 km2 and ranges in elevation from 460 m along Arroyo Tepoca near Curea to 2240 m on the highest point of Mesa del Campanero in an airline distance of 25 km, an elevational gradient of 71.2 m\km. Mesa del Campanero is one of the highest points in eastern Sonora. The Municipio from 109°17'W west of Tepoca to 108°31'W near the Chihuahua border is 76 km wide by air and 145 kilometers along MEX 16. Principal towns are Tepoca, Yécora, Maycoba, and El Kípor along the highway and Agua Blanca, La Concepción, Curea, Guadalupe Tayopa, La Quema, San Nicolás, Santa Ana, Santa Rosa, and La Trinidad along secondary roads. Most of the area is in the Río Yaqui drainage. Only a very small area near El Bordo on the west slope of Mesa del Campanero drains to the Río Mayo.
The families with the greatest number of taxa are the Asteraceae (Compositae, 251), Poaceae (Gramineae, 188), Fabaceae (Leguminosae, 177), and Euphorbiaceae (57). This is typical of temperate floras and unlike tropical deciduous forests which have greater numbers of legumes. (Tropical vegetation occurs below 1000 m in the Municipio de Yécora.) The most numerous genera are Muhlenbergia (34, a grass), Euphorbia (31, spurges), Dalea (22), Quercus (14 plus 6 hybrids, oaks), Cheilanthes (16, ferns), and Salvia (20, mints). Other interesting plants in the area include milkweeds, cacti, begonias (Begonia spp.), perico cimarrón (Tigridia pavoniana), wild hydrangea (Hydrangea seemannii), lilies), agaves, and orchids. Over 30 taxonomic specialists helped with species identifications and specimens have been deposited into many herbaria in the United States and Mexico.
References Martin, P. S., D. Yetman, M. Fishbein, P. Jenkins, T. R. Van Devender, and R. K. Wilson. 1998. Gentry's Río Mayo plants. The tropical deciduous forest and environs of northwest Mexico. University of Arizona Press, Tucson, AZ. Reina G., A. L., T. R. Van Devender, W. Trauba, and A. Búrquez M. 1999. Caminos de Yécora. Notes on the vegetation and flora of Yécora, Sonora. Pp. 137-144 in D. Vasquez del Castillo, M. Ortega N., C. A. Yocupicio C. (eds.), Memorias: symposium internacional sobre la utilización y aprovechamiento de la flora silvestre de zonas arida. Departamento de Investigaciones Científicas y Tecnológicas de la Universidad de Sonora, Hermosillo, Sonora, Mexico. Van Devender, T. R., J. R. Reeder, C. G. Reeder, and A. L. Reina G. In press. Distribution and diversity of grasses in the Yécora region of the Sierra Madre Occidental of eastern Sonora, Mexico. In J.-L. E. Cartron, G. Ceballos, and R. S. Felger (eds.), Biodiversity, ecosystems, and conservation in northern Mexico. Oxford University Press, New York, NY.
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