Nellie Cory Cactus

Coryphantha minima

Description

The dwarf Nellie cory cactus, Coryphantha minima, grows up to 1.5 in (4 cm) high and 0.8 in (2 cm) in diameter. The stems are simple or branching, and either egg-shaped or cylindrical. The ash gray or pink spines are in clusters (areoles) of about 20. The unique club-shaped spines thicken toward the end then taper abruptly to a point. Rose or purple flowers bloom in May; fruits mature by early June. Heavy rains dislodge the seeds and runoff carries them away from the base of the cactus. Plants are often covered with spikemoss. Information on this plant has also been published under other scientific names: Coryphanta nellieae, Escobaria nellieae, and Mammillaria nellieae.

Habitat

This cactus species grows in Chihuahuan Desert grassland and is restricted to the Caballos Novaculite Formation, a series of rocky outcrops that form low-lying ridges highly resistant to erosion. These ridges support perennial bunch grasses and a wide variety of shrubs and cacti. The Nellie cory cactus is usually found growing among chips of weathered and fractured novaculite (a silica-bearing rock). Habitat elevation is between 3,960 and 4,455 ft (1,200 and 1,350 m); average annual rainfall is about 16 in (41 cm).

Distribution

Nellie cory cactus is endemic to the Chihuahuan Desert of northern Brewster County, Texas, in the Big Bend region. It is believed to have developed within a very limited range. The cactus is found in two separate populations on private land near the town of Marathon in Brewster County. When the recovery plan was issued in 1984, the total population was estimated at about 40,000-80,000 plants. Population densities vary widely, from several hundred plants per square meter to no plants at all in nearby areas. Seedlings were found throughout the population, and their success rate is estimated at fair to good.

Threats

Nellie cory cactus is threatened on several fronts. The major threat is from commercial cactus dealers who collect this highly prized cactus from the wild. Although the dwarf size of the cactus makes it difficult to find, its dense populations are easily located and harvested. Additionally, the low population numbers and extremely restricted distribution worsen the threat. A highway that cuts through the habitat undoubtedly destroyed many individuals and renders the population easily accessible to collectors. Livestock grazing and trampling, modification to the habitat, brush control—through the use of herbicides—to cultivate pastures are potential threats, as are novaculite mining, and highway and fence maintenance.

Conservation and Recovery

As with many other cacti, the major recovery strategy aims at reducing commercial collecting. Because the cactus grows readily in cultivation, botanists will initiate a propagation program to supply the commercial market in sufficient quantities to bring down the high price that wild plants now command, making collection from the wild less profitable. A second part of the strategy is to arrest and prosecute illegal collectors and publicize the fact in trade publications. The plant is protected by the state of Texas.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

References

Brown, D. 1982. "Desert Plant-Biotic Communities of the American Southwest—United States and Mexico." Report. University of Arizona, for Boyce Thompson Southwestern Arboretum, Superior, Arizona.

U. S. Fish and Wildlife Service. 1987. "Endangered and Threatened Species of Texas and Oklahoma (with 1988 Addendum)." U. S. Fish and Wildlife Service, Albuquerque.

U. S. Fish and Wildife Service. 1984. "Nellie Cory Cactus Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.

Weniger, D. 1979. Cacti of the Southwest. University of Texas Press, Austin.