Physiognomy and Structure: This vegetation has a sparse to dense herbaceous layer less than 1 m tall that is dominated by perennial mid- and shortgrass species. Sparse to scattered cover of shrubs may be present. Perennial forbs are common but are not abundant in most stands. Annual forbs and grasses are seasonally present.

Floristics: Grasslands included in this alliance are characterized by a sparse to moderately dense herbaceous layer dominated by the medium-tall, cool-season bunchgrasses Aristida purpurea, Bouteloua gracilis, Hesperostipa comata, or Sporobolus cryptandrus. Other common to codominant graminoids include Achnatherum hymenoides (= Oryzopsis hymenoides), Carex filifolia, Koeleria macrantha, Pleuraphis jamesii (= Hilaria jamesii), Poa secunda, Sporobolus contractus, and Sporobolus giganteus. The invasive species Bromus tectorum is common in disturbed stands. Shrubs and dwarf-shrubs are sparse and may include scattered Artemisia cana, Artemisia frigida, Artemisia tridentata, Ericameria nauseosa (= Chrysothamnus nauseosus), or Gutierrezia sarothrae. Forb cover is also sparse, but can be relatively diverse. Common forbs are Gaura coccinea, Lappula occidentalis (= Lappula redowskii), Lithophragma glabrum, Lithophragma glabrum, Lupinus pusillus, Opuntia aurea (= Opuntia basilaris var. aurea), Opuntia polyacantha, Plantago patagonica, or Pediomelum argophyllum (= Psoralea argophylla). Cryptogams are important in some stands with up to 40% ground cover on sites in the Colorado Plateau.

Dynamics:  These grasslands are dominated by relatively deep-rooted grasses that use soil moisture below 0.5 m during the typically dry summers. The coarse-textured soils allow for rapid infiltration and storage of winter and summer precipitation (Kleiner 1968, Daubenmire 1970, Kleiner and Harper 1977, Thilenius et al. 1995). Burning generally kills or severely damages Hesperostipa comata plants. After fire, regeneration of this non-rhizomatous bunchgrass is through seed and may take many years to reach prefire densities (FEIS 1998). Exotic species such as Bromus tectorum, Draba verna, Lactuca serriola, Tragopogon dubius are present in some these stands (Daubenmire 1970). The cool-season annual grass Bromus tectorum can be an effective competitor for winter soil moisture because it can germinate in the fall, overwinter, then begin regrowing in the early spring before it is warm enough for many perennial grasses, completing its lifecycle and depleting soil moisture before the dry summer weather begins. This annual species also produces abundant fine fuels that carry fire well and increase the frequency of fires (FEIS 1998).Bouteloua gracilis is an extremely drought- and grazing-tolerant shortgrass species. It 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.