Shadscale/marsh zone (<4,200 ft)
 

Alkaline desert scub vegetation of the Alvord Desert below approx 4,200 feet. is dominated by shadscale, fourwing saltbrush, greasewood, spiny hopsage, saltgrass, and other halophytes. This vegetation zone is also in the Harney Basin and the Catlow Valley. However most of the Harney Basin at the base of Steens Mountain contains the freshwater Malheur marsh. Ash crops, sand dunes, barren clay soils, and a variety of wetlands including riparian meadows and woodlands, ponds, and hot springs area laso present in this zone.

The lower flanks of Steens Mountain from approx. 4,200-5,400 feet are dominated by mountains big sagebrush, low sagebrush, common rabbitbrush, and a variety of grasses and forbs. Most of the west side of Steens has been planted in crested whetgrass. Western Juniper extends through this zone from above along basaltic fractures occupiedby wax current and other shrubs. Riparian woodlands dominated by willow, alder, birch, currents, cottonwood, cherries, and dogwood. These interupt the large expanses of sagebrush scrub. 

Western juniper dominates the vegetation between 5,400 - 6,500 feet. Seasonally moist depressions, vernal pools, clay barrens, riparian meadows, seeps, gorge-bottom woodlands and mesic north-facing aspen dominated slpoes all contribute to the habitat diversity in this zone.

The "subalpine" elevation of Steens Mountain are a mosaic of aspen stands, sagebrush grasslands, rimrock/talus, and riparian meadows. The absence od subalpine conifers is evident in other northern Great Basin ranges, but none as large as Steens. The absence of subalpine conifers is probably related to Steens' isoloation. 

Alpine bunchgrass/tundra zone (>7,900 ft)
 

The highest elevation of Steens, above approx. 7,900 feet, has been referred to as either subalpine grassland or true alpine tundra. The alpine vegetation of Steens Mountain is developed best in the wetter sites. Within the alpine belt several distinct habitats can be recognized. The dry, gravelly, windswept summit ridges and dry bunchgrass communities below the ridge crest. An assortment of alpine wet medows, talus and scree slopes, snowbanks, rock outcrops, and riparian are also evident of Steens.