Achnatherum speciosum Herbaceous Alliance
Desert needlegrass grassland

USDA Ecological Section Map

Summary Information

  • Primary Life FormHerb
  • Elevation0-3400 m
  • State RarityS2.2
  • Global RarityG4
  • DistributionCAN: BC: USA: CA, NV, CO?, NM?, OR?, WA?. Mexico? (TJM2) (USDA Plants)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsNo
  • Date Added1995/11/01

Characteristic Species

Achnatherum speciosum is dominant or co-dominant in the herbaceous layer with Achnatherum hymenoides, Elymus elymoides, Nassella cernua, Nassella lepida and Poa secunda. Emergent trees and shrubs may be present at low cover, including trees Juniperus californica or Yucca brevifolia and shrubs:Ambrosia salsola, Artemisia tridentata, Coleogyne ramosissima, Ericameria cooperi, Ericameria linearifolia, Ericameria teretifolia, Grayia spinosa and Krascheninnikovia lanata.

Vegetation Layers

Herbs < 1 m; cover is open to intermittent.

Membership Rules

  • Achnatherum speciosum > 50% relative cover in the herbaceous layer (Thomas et al. 2004).


Lower slopes, swales, rocky hills, flat ridges, talus slopes, and , and in canyons, and on sandy or gravelly alluvial fans. Soils are coarse- textured with no profile development.

Other Habitat, Alliance and Community Groupings

MCV (1995) Desert needlegrass series
NVCS (2009) Achnatherum speciosum herbaceous alliance
Calveg Perennial grasses and forbs
Holland Mojave mixed steppe, Native grassland
Munz Creosote bush scrub
WHR Desert scrub, Perennial grassland
CDFW CA Code 41.090.00

National Vegetation Classification Hierarchy

Formation Class Xeromorphic Scrub and Herb Vegetation (Semi-Desert)
Formation Subclass Cool Semi-Desert Scrub and Grassland
Formation Cool Semi-Desert Scrub and Grassland
Division Western North American Cool Semi-Desert Scrub and Grassland
Macro Group Inter-Mountain Dry Shrubland and Grassland
Group Southern Great Basin semi-desert grassland group