Colorado Hookless Cactus (Sclerocactus glaucus)

Sclerocactus Glaucus in flower Photo Credit: Linda Stoneman

Global Rank: G2 - Imperiled
Legal Status: Federally Threatened
Family: Cactaceae
State: CO, UT
Nature Serve ID: 832412
Lifeform: Shrub
Categories of Interest: Cacti/Succulents
Date Inducted in National Collection:

Description:

Sclerocactus glaucus, the Uinta Basin hookless cactus flowers from April to May, and after blooming may shrink below the ground. Thus plants are often only visible while blooming, when they have bright pink flowers. S. glaucus and S. parviflorus look similar, but S. parviflorus has a hooked central spine and is larger than S. glaucus. Since listing, the taxonomic status of Sclerocactus glaucus has been through many iterations ranging from one to three species. Hochsttter (1993) split the species into two distinct species, S. glaucus and S. wetlandicus var. ilseae Hochsttter (later termed S. brevispinus). Hochsttter (1997) later divided the species further into three distinct taxonomic units, S. glaucus, S. brevispinus Heil & Porter, and S. wetlandicus, a split which represents the currently accepted taxonomy (FNA 2004, USFWS 2007). Taxonomy within the genus Scelerocactus is notoriously difficult due to shifts in the morphology of a species throughout its lifetime (i.e. juvenile vs. reproductive, primary stem vs. secondary stems). All parts of the stems, spines, and flowers express great variation throughout the life cycle making species-level identification difficult (Heil & Porter, 1994). In general the genus is characterized by perennial stems which may shrink into the soil during the winter, confounding species identification when not in flower. Hybridization is very common in the genus, further complicating species identification in areas of sympatric populations (Heil & Porter 1994).

Where is Colorado Hookless Cactus (Sclerocactus glaucus) located in the wild?

Habitat:

Populations of S. glaucus occur on alluvial benches and lower mesa slopes along the Green, Colorado, and Gunnison Rivers. Soils are usually coarse, gravelly river alluvium above the river flood plains. Mancos shale with volcanic cobbles and pebbles form surface material. Elevations range from 1200-2000 m. Associated vegetation is typically desert scrub dominated by Atriplex confertifolia, Hilaria jamesii, Artemesia nova, and Stipa hymenoides. Other important species include Echinocereus triglochidiatus var. melanacanthus, Pediocacus simpsonii, Opuntia polycantha, Krascheninnikovia lanata, Yucca harrimaniae, Gutierrezia sarothrae, Crysothamnus viscidiflorus, Sporobolus cryptandrus, and Elymus salinus.

Distribution:

Sclerocactus glaucus is a regional endemic to western Colorado and eastern Utah. There are 90-100 element occurrences in Colorado and 36 in Utah, but many of these occurrences have very few individual

States & Provinces:

Colorado Hookless Cactus can be found in Colorado, Utah

Which CPC Partners conserve Colorado Hookless Cactus (Sclerocactus glaucus)?

Denver Botanic Gardens

Partially Sponsored

Conservation Actions

09/28/2020

Denver Botanic Gardens Research staff established permanent macroplots in two populations of S. glaucus in the Escalante Canyon area in 2007, and established two additional macroplots in 2008, one in the Escalante Canyon area and one near Debeque. The goal of the monitoring is to record demographic trends in populations of S. glaucus.

Nature Serve Biotics

05/02/2017

This species is a regional endemic of western Colorado and adjacent Utah. There are 90-100 element occurrences in Colorado, and 36 in Utah (CNHP 2003, UCDC 2003). Nearly all populations are threatened with habitat destruction or modification from development of energy extraction, water storage projects, transportation, and residental facilities. Other ongoing threats include impacts from moss-rock and rip-rap collecting operations, illegal collection and damage by recreational use or livestock trampling. Although total element occurrence numbers suggest a possible rank of G4, the restricted range and the pervasive nature of threats to its habitat constitute the primary justification for the global rank of G3.