Herbaceous plants, such as bush muhly (Muhlenbergia porteri), blue grama (Bouteloua gracilis), gypsum grama (B. breviseta), and hairy grama (B. hirsuta), are dominant in desert grasslands and near the mountain edges including the Sierra Madre Occidental. Lechuguilla (Agave lechuguilla), honey mesquite (Prosopis glandulosa), Opuntia macrocentra and Echinocereus pectinatus are the dominant species in western Coahuila. Ocotillo (Fouquieria splendens), lechuguilla, and Yucca filifera are the most common species in the southeastern part of the desert. Candelilla (Euphorbia antisyphilitica), Mimosa zygophylla, Acacia glandulifera and lechuguilla are found in areas with well-draining, shallow soils. The shrubs found near the Sierra Madre Oriental are exclusively lechuguilla, guapilla (Hechtia glomerata), Queen Victoria's agave (Agave victoriae-reginae), sotol (Dasylirion spp.), and barreta (Helietta parvifolia), while the well-developed herbaceous layer includes grasses, legumes and cacti.