Physiognomy and Structure: Stands in this alliance have a graminoid layer dominated by short grasses that typically form a sod. Midgrasses may be present to codominate in some communities. Rarely, sparse scattered shrubs may be present. Some ungrazed stands may have a short bunchgrass form.

Floristics: This vegetation of this shortgrass prairie alliance is characterized by a moderate to dense sod of short grasses with scattered midgrasses and forbs. The dominant and diagnostic species are Bouteloua gracilis and Bouteloua dactyloides (= Buchloe dactyloides). Other short graminoids include Bouteloua hirsuta, Carex duriuscula, Carex inops ssp. heliophila, and Carex filifolia. Midgrasses, if present, are usually stunted by the arid conditions and often do not exceed 0.7 m in height. They include Aristida purpurea, Bothriochloa saccharoides, Bouteloua curtipendula, Elymus elymoides, Hesperostipa comata (= Stipa comata), Muhlenbergia torreyi, Pascopyrum smithii, Pleuraphis jamesii, Schizachyrium scoparium, and Sporobolus cryptandrus. Characteristic forbs such as Astragalus spp., Eriogonum jamesii, Gaura coccinea, Machaeranthera pinnatifida var. pinnatifida, Opuntia polyacantha, Plantago patagonica, Psoralidium tenuiflorum, Ratibida columnifera, Sphaeralcea coccinea, and Zinnia grandiflora are common. Scattered shrubs are rare and may include Artemisia frigida, Atriplex canescens, Ericameria nauseosa (= Chrysothamnus nauseosus), Gutierrezia sarothrae, Yucca glauca, and Cylindropuntia imbricata (= Opuntia imbricata) (in the southern extent).

Dynamics:  Large-scale processes such as climate, fire and grazing constitute the primary processes impacting this alliance. The short grasses that dominate this alliance are extremely drought- and grazing-tolerant (Lauenroth and Milchunas 1992, Lauenroth et al. 1994, Milchunas and Lauenroth 2008). Bouteloua gracilis is one of the most widely distributed grasses in the western U.S. and is present in many different grassland, shrubland and woodland communities. It evolved with grazing by large herbivores and generally forms a short sod. However, in some stands, ungrazed plants develop the upright physiognomy of a bunchgrass. If Bouteloua gracilis is eliminated from an area by extended drought (3-4 years) or disturbance such as plowing, regeneration is slow because of very slow tillering rates (Samuel 1985), low and variable seed production (Coffin and Lauenroth 1992), minimal seed storage in the soil (Coffin and Lauenroth 1989c) and limited seedling germination and establishment due to particular temperature and extended soil moisture requirements for successful seedling establishment (Hyder et al. 1971, Briske and Wilson 1978, 1980). Bouteloua dactyloides is often abundant in swales and depressions. It is less drought-tolerant than Bouteloua gracilis, but following disturbance re-establishes more quickly via seeds and above-ground tillering (Peters et al. 2008).