General description: A squat, globular, spiny succulent. Each mature stem is 3-12 cm tall, 4-9 cm wide; the largest observed was 24 cm tall x 14 cm wide (DeYoung 2010). However, during the driest part of the year the stem may shrink to below ground-level. Central spines are straight (hookless). The plants are inconspicuous except when in flower (April-May), when showy, fragrant, pink to magenta flowers appear at the top of the stem.

Look Alikes: Distinguished from Scelerocactus parviflorus by the absence of a strongly hooked central spine (Weber and Wittmann 2012). 

Phenology: Plants are readily visible when flowering, usually late April and early May. After flowering, their dull greyish green color makes them difficult to see. During extended dry periods the stems may shrink to below ground level. Fall rains may cause them to swell up again and become easier to see (Spackman et al. 1997).

Populations occur primarily on alluvial benches along the Colorado and Gunnison Rivers and their tributaries. Sclerocactus glaucus generally occurs on gravelly, or rocky surfaces on river terrace deposits and lower mesa slopes. Exposures vary, but S. glaucus is more abundant on south-facing slopes. Soils are usually coarse, gravelly river alluvium above the river flood plains usually consisting of Mancos shale with volcanic cobbles and pebbles on the surface. Elevations range from 1200-2000 m. Associated vegetation is typically desert scrub dominated by shadscale (Atriplex confertifolia), galleta (Hilaria jamesii), black-sage (Artemisia nova), and Indian rice grass (Stipa hymenoides). Other important species include two similar spherical or cylindrical cactus species, strawberry hedgehog cactus ( Echinocereus triglochidiatus var. melanacanthus) and Simpson's pincushion cactus (Pediocactus simpsonii). Other important species in the plant community include the prickly pear cactus (Opuntia polyacantha), winterfat (Krascheninnikovia lanata), yucca (Yucca harrimaniae), snakeweed (Gutierrezia sarothrae), low rabbitbrush (Chrysothamnus viscidiflorus), sand dropseed (Sporobolus cryptandrus), and Salina wildrye (Elymus salinus) (USFWS 1990, Scheck 1994). Fire is not typically characteristic of S. glaucus habitat, but areas with large infestations of cheatgrass (Bromus tectorum) may build up sufficient fuel to carry fire into S. glaucus populations.  
Exposed, gravel-covered, clay hills, saltbush or sagebrush flats, or pinyon-juniper woodlands; 1400-2000 m (Flora of North America Editorial Committee 2003).

Elevation Range: 4,646 - 7,126 feet (1,416 - 2,172 meters)

Colorado endemic: Yes
Global range: Known from Delta, Garfield, Mesa, and Montrose counties in Colorado. Estimated range is 3307 square kilometers (1277 square miles), with the northern population covering 505 square kilometers, and the southern population 2802 square kilometers. Values calculated in GIS by the Colorado Natural Heritage Program in 2017 following NatureServe methodology.

Habitat destruction or modification by development of energy extraction, water storage projects, transportation, and residental facilities constitutes the greatest threat to S. glaucus. This threat is wide-ranging, increasing, and less amenable to mitigation than are the threats of illegal collecting or disturbance by agricultural or recreational activities. The scope and severity of this threat are inferred from numbers of plants known to be impacted by projects such as the TransColorado gas transmission pipeline and Colorado Highway 50 widening, as well as anecdotal observations from field personnel familiar with the species. Cheatgrass (Anisantha tectorum) invasion is also causing considerable degradation of S. glaucus habitat in some areas.