Colorado hookless cactus

<em>Sclerocactus glaucus</em>, the Colorado hookless cactus, is a small, barrel-shaped cactus in the family Cactaceae endemic to the Colorado River drainage basin in the western United States. This species is assessed as Least Concern by the IUCN, though it is listed as a threatened species under United States federal law, reflecting localised population pressures from habitat disturbance, off-road vehicle activity, and illegal collection. <em>Sclerocactus glaucus</em> inhabits diverse terrestrial environments including semi-arid shrublands, clay badlands, and river terraces at low to moderate elevations in Colorado and Utah. The species is characterised by its blue-green stem colour and the absence of the hooked central spines found in related species, a feature encoded in its common name. Flowers are typically pink to lavender and appear in spring. As a slow-growing perennial, this cactus is vulnerable to prolonged disturbance and recovery from population setbacks may require decades. Pollinators including native bees are essential for fruit and seed production. Biological traits of this species remain poorly documented in the scientific literature.