Physiognomy and Structure: Vegetation in this alliance is characterized by a moderate to dense cover of graminoids that is dominated by perennial bunch grasses. There is also a sparse to moderate cover of perennial forbs. Annual forbs and grasses are seasonally present.

Floristics: Vegetation included in this alliance has a moderately sparse to dense herbaceous layer, depending on the amount of rock cover. These grasslands are characterized by an open to dense perennial graminoid layer composed bunchgrasses, especially Festuca thurberi and Danthonia intermedia. Other diagnostic and sometimes dominant species include Achnatherum richardsonii, Danthonia parryi, Festuca idahoensis, Geranium viscosissimum, Lathyrus lanszwertii var. leucanthus, Poa lettermanii, Poa nervosa, Potentilla hippiana, Solidago multiradiata and Sporobolus heterolepis. Muhlenbergia montana and Festuca arizonica may be present to codominant (on warmer/drier sites). These grasslands have high diversity of species. Other characteristic graminoids may include Agrostis variabilis, Bromus spp., Carex engelmannii, Carex geyeri, Carex haydeniana, Carex microptera, Carex siccata (= Carex foenea), Carex scirpoidea, Danthonia parryi, Elymus trachycaulus, Festuca brachyphylla, Juncus drummondii, and Trisetum spicatum. Forb species are diverse and may codominate the herbaceous layer with species such as Achillea millefolium, Arenaria capillaris, Artemisia spp., Cerastium beeringianum, Erigeron simplex, Erigeron speciosus, Erigeron ursinus, Eriogonum umbellatum var. majus (= Eriogonum subalpinum), Geum rossii var. turbinatum, Hymenoxys hoopesii, Iris missouriensis, Lewisia pygmaea, Minuartia obtusiloba, Polygonum bistortoides, Potentilla diversifolia, Saxifraga rhomboidea, Solidago multiradiata, Symphyotrichum foliaceum (= Aster foliaceus), Vicia americana, and many others. On moist sites Veratrum californicum may be codominant. Grazed stands often have moderate cover of non-native species such as Poa pratensis and Taraxacum officinale. The ground surface is often covered with nonvascular plants such as lichens, liverworts, and mosses forming a biological crust. Adjacent stands include subalpine conifer woodlands, and herbaceous- or shrub-dominated wetlands.

Dynamics:  Festuca thurberi grasslands typically have sharp ecotones with adjacent Picea engelmannii- and Abies lasiocarpa-dominated subalpine forests. There is rarely any invasion by tree seedlings in the adjacent grasslands. These high-elevation meadows are typically dry with southern or western aspects. The soils are deep and well-developed, typical of sites with long histories of being grassland. They may need catastrophic disturbance, such as forest-destroying crown fire, to be created. It is unclear how these grasslands were maintained in the subalpine forest zone; however, it is thought to be by a combination of factors such as herbivory, fire, deep soils, early summer drought and competition from grass species (Moir 1967, Andrews 1983). In addition, south- and west-facing clearcuts are often difficult to reforest because seedlings are damaged by full sun. The ecotones between stands adjacent to Populus tremuloides-dominated subalpine forests are not as sharp because the forest understory consists of the same graminoid and forb species (Anderson 1983).

Where the soil is thinner and rockier in these subalpine parks, Danthonia parryi becomes the dominant species with Festuca thurberi and Artemisia spp. subdominant (Anderson 1983). The spread of the exotic species Poa pratensis and Taraxacum officinale in subalpine parks is likely from heavy grazing by livestock (Moir 1967, Anderson 1983). These species are more common in heavily grazed bottomlands and near trails in the uplands (Moir 1967).