The Tropical Madrean Flora of Yecora, Sonora, Mexico

The Municipio de Yécora is in the Tropical Madrean zone of the Sierra Madre Occidental in eastern Sonora, Mexico. The flora is very diverse with 1777 taxa in 150 families and 687 genera. The most important families and genera are Asteraceae (14.5% of the flora), Poaceae (11.3%), and Fabaceae (10.6%), Muhlenbergia (38 taxa), Euphorbia (31 taxa), Cyperus (29 taxa), Ipomoea (26 taxa), Quercus (23 taxa including 7 hybrids), and Dalea (22 taxa). Herbaceous plants dominate the flora (71.3%). Twenty-one species in the Yécora flora have protection in NOM-059-SEMARNAT- 2010. Non-native species are 6.2% of the flora but only buffelgrass (Pennisetum ciliare) in the tropical lowlands and Natal grass (Melinis repens) in grassland and oak woodland are invasive in natural habitats.

Vegetation is zoned from foothills thornscrub and tropical deciduous forest in the lowlands to oak woodland and pine-oak forest in the uplands. Plant species diversity increases with elevation and rainfall, peaking in pine-oak forest. The Yécora flora in the Madrean Tropical Madrean zone serves as a baseline to evaluate Madrean affinities in floras in the Madrean Archipelago in northeastern Sonora and southeastern Arizona.