Shrubs dioecious (rarely monoecious), low spreading (often appearing as if prostrate), mainly 0.3-1.5 × 3-15 dm. Leaves persistent, sessile, opposite proximally, alternate distally; blade linear to linear-oblanceolate, or oblong, 3-18 × 2-6 mm, margin entire, apex obtuse. Staminate flowers yellow to brownish, in clusters 3-6 mm wide, borne in spikes 1-8 cm. Pistillate flowers in leafy bracteate spikes 5-15 cm. Fruiting bracteoles sessile or subsessile, panduriform, 3-5 × 4-6 mm, united to beyond middle, margin entire or undulate, apex rounded to acute, densely tuberculate (or smooth). Seeds brown, 1.5 mm wide. 2n = 36.

Flowering spring-fall. Saline, usually fine-textured substrates derived from Mancos Shale, Tropic Shale, Morrison, Duchesne River, and other similar formations in mat-atriplex and Castle Valley saltbush communities; 1200-2200 m; Colo., N.Mex., Utah.

Mat-saltbush is known to form intermediates with both Atriplex confertifolia and A. gardneri var. cuneata. This saltbush is a valuable browse plant on the sparsely vegetated clays and silts of eastern Utah, especially on the Mancos Shale exposures, where it is often the only woody vegetation present.