Physiognomy and Structure: This alliance is dominated by mid grasses. The vegetation cover can be moderately sparse to dense. Short graminoids contribute substantially to the vegetation cover in most communities. The short grasses tend to be more common on flat uplands or steep slopes with heavier soils (Weaver and Albertson 1956). Trees and shrubs are rare to absent.

Floristics: Schizachyrium scoparium is the dominant grass but other mid and short grasses and sedges can be abundant, particularly Bouteloua curtipendula, Bouteloua gracilis, Carex inops ssp. heliophila, and Carex filifolia. In a few stands in eastern Montana and possibly western North Dakota, Muhlenbergia cuspidata can be a codominant. Several other mid or tall grasses can be present, including Andropogon gerardii, Calamovilfa longifolia, Hesperostipa comata, Koeleria macrantha, Nassella viridula, and Pascopyrum smithii. Forb species richness is high, but cover is low (15-20%). Artemisia ludoviciana and Phlox hoodii are the most common forbs. Other forbs may include Astragalus gracilis, Cerastium arvense, Echinacea pallida, Gaura coccinea, Helianthus pauciflorus (= Helianthus rigidus), Heterotheca villosa, Pediomelum argophyllum (= Psoralea argophylla), and many others. Scattered short shrubs and dwarf-shrubs (<5% cover) may be present such as Artemisia cana, Artemisia frigida, Calylophus serrulatus (= Oenothera serrulata), Rhus trilobata, Rosa arkansana, and Symphoricarpos occidentalis. Annual forbs and grasses may be seasonally present, especially in disturbed areas.

Dynamics:  These grasslands are dominated by deep-rooted perennial mid grasses that are able to utilize moisture that penetrates deep into these well-drained, coarse-textured soils (Morris and Lovegrove 1975). Fire is important to prevent the invasion of these vegetation types by woody species. However, fire is not as important as in more mesic grasslands, because drought conditions slow encroachment by woody species.