COLORADO'S RARE CACTI: Sclerocactus glaucus, by Jim Ratzloff

Aquilegia, Vol. 1, No. 4, July – August 1977

Sclerocactus glaucus (K. Schum) L. Benson is western Colorado cacti that is proposed endangered on the Federal Register list of endangered plants. This “brill” cactus is very little known! only rarely finding its way into cactus books or plant manuals. Its usually solitary stems have a squat, flattened globe appearance, growing only two to four inches tall. There are 7 to 11 spines at each “eye” (areole)
of the stem. Most of the spines are white, with the exception of one long, brown spine, called the lower central spine, which comes straight out of the center of each eye. The spine-covered eyes of are at the tip of nipple-like structures, tubercles. In mature plants, the tubercles are aligned into vertical rows called ribs. Each Sclerocactus glaucus stem typically has 12 ribs.

Sclerocactus glacus, Photo by Gina Glynne.

This rare cactus is found in west-central Colorado and northeast Utah. In Colorado it grows at about 4,500 to 5,500 feet. It blooms for a brief period in early spring. The flowers are a deep pink, with many petals, many stamens, one style and a lobed stigma. The stamens and stigma become “ripe” at different times, which ensures that cross-pollination of the flower takes place.

If the bright, showy flowers of Sclerocactus glaucus are not present to give a clue to its location, the plant is very difficult to see because its squat appearance and drab spines blend into the surrounding soil and rocks. Even while it is blooming, one can walk through Sclerocactus glaucus’s habitat in the morning and see very few, if any, of its stems. If the same area is walked over after the flowers open in early afternoon, many stems will be found. This evasive cactus blooms in the afternoons for a period of about two weeks, then seems to vanish into the surrounding terrain until it blooms again a year later.

Sclerocactus glaucus’s elusive nature during most of the year protects it somewhat from the most serious danger to rare cacti in the Southwest–over-collecting by cactus dealers and hobbyists. This exploitation first became a problem in Arizona,

which was also the first state to pass stringent laws regulating the collection of cacti. The cactus collectors then began heavy collecting just across the Arizona border In California. California is now trying to stop this exploitation with newly-drafted laws to protect its native plants. Once the new California laws are enforced, an increase in the collection of cacti in the Nevada and Utah deserts is expected, where the stealing already is heavy.*

What this clearly indicates is that the stealing of cacti from western Colorado’s desert lands, which now occurs, can only be expected to increase in the future. Sclerocactus glaucus along with the other Colorado cacti listed as proposed endangered in the Federal Register, will eventually be legally protected if they receive a final endangered status by the U.S. Fish and Wildlife Service. Additional state legislation, however, would strengthen the protection of Colorado’s rare cacti beyond the federal laws. State laws protecting native plants similar to Arizona’s and California’s may be desirable, and possibly necessary to protect this limited resource before it is appreciably decreased or lost by over-collecting. Rare cacti are very possibly the Colorado native plants which are in the most serious danger, since they are commercially exploited, and no time should be lost in taking steps to protect them.

photo of physaria ovalifolia in flower and fruit

Sclerocactus glaucus, photo by Lauri Bremmer.

* Richard Countryman, Assistant Director, Arizona Commission of Agriculture and Horticulture, in B.L.M. Newsbeat. March 1977.

Editor’s Note: Sclerocactus glaucus was listed as threatened by the U.S. Fish and Wildlife service on October 11, 1971. Sclerocactus glaucus is endemic to Colorado with 93 occurrences, 21 of which have not been seen in over 20 years. Besides illegal collection, the species is considered to be at high risk due to habitat destruction by energy development activities, water storage projects, transportation, and residential development.