Pima Pineapple Cactus

Coryphantha scheeri var.robustispina

Description

The pima pineapple cactus is a hemispherical cactus measuring 4 to 18.4 in (10 to 46 cm) tall and 3 to 7.2 in (7.5 to 18 cm) in diameter. The spine clusters have one centralized spine that is especially strong and usually hooked. The spines are short and light yellow; with age the spines turn black. This plant may be single-stemmed, multi-headed, or in clusters. The clustered appearance is a result of the seeds germinating at the base of a mother plant or when a tubercle of the mother plant roots. The flowers are a silky yellow and appear in July through August. The green fruit is ellipsoidal, succulent and sweet.

Habitat

This cactus grows in alluvial basins or on slopes in semidesert grassland and Sonoran desert-scrub. Soils range from shallow to deep, and silty to rocky. It seems the pima pineapple cactus prefers silty to gravelly deep alluvial soils. This plant occurs most frequently in open areas on flat ridgetops or areas with very little slope at an elevation of 2,296 to 4,593 ft (700 to 1,400 m). Associated vegetation includes white-thorn acacia, creosotebush, velvet mesquite, triangle-leaf bursage, thread snakeweed, chain fruit cholla, Isocoma tenuisecta, Lehman's lovegrass, and other cacti species.

Distribution

The pima pineapple cactus is known from Pima and Santa Cruz Counties, Arizona and northern Sonora, Mexico.

The range of this cactus extends from the Baboquivari Mountains east to the western foothills of the Santa Rita Mountains. It is difficult to ascertain the area of potential habitat for this species due to its habitat requirements and the topographic complexity within its range.

The population density is difficult to attain as well because the pima pineapple cactus is difficult to find in the field. Minimum density estimates for areas near the Sierrita Mountains of Arizona range from a low of 0.3 plants per acre (0.12/ha) to 1.3 plants per acre (0.54/ha).

This plant must compete for space, light and nutrients with exotic vegetation. Some plants seem to be damaged by the larval stage of lepidoptera.

Threats

The pima pineapple cactus is currently threatened by many factors including illegal collection, habitat degradation due to recreational activities, habitat destruction by livestock, and habitat loss due to mining, agriculture, road construction, and urbanization.

It is approximated that about 75% of the pima pineapple cactus's range is threatened by construction associated with growing human populations. Home building, commercial development, road construction and maintenance, and utility corridor construction are only a few of the activities destroying this species's habitat.

Mining activities have resulted in the loss of hundreds of pineapple cacti because they were not salvaged before expansion. Mineral extraction activities such as road access, tailing piles and settling or leaching ponds have also adversely affected this species.

Those areas that are currently undeveloped are utilized for livestock grazing. Over-grazing has most likely resulted in the current alteration of the ecosystem in this area. Erosion; changes in hydrology and microclimate; invasion of exotic vegetation; shifts in density, relative abundance, and vigor of native species; and increases in woody perennials have all been a result of this overgrazing.

This species is also faced with competition from aggressive exotics such as Lehman's lovegrass and Mediterranean grass.

Conservation and Recovery

Conservation of the Pima pineapple cactus requires the protection of its critical habitat, most of which is on privately owned land. These habitats should be protected by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the owners. All critical habitats must be better protected from illegal collecting of plants by amateurs and for commercial trade. The populations of the Pima pineapple cactus should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices. The rare plant should be propagated in captivity to provide stock for out-planting to increase the size of existing populations and to establish new ones in suitable habitat. Surveys should be made in the Mexican range of the rare plant to determine its status there.

Contacts

U.S. Fish and Wildlife Service
Office of the Regional Director
P.O. Box 1306
500 Gold Avenue SW
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6282
Fax: (505) 248-6845

U.S. Fish and Wildlife Service
Division of Endangered Species and Habitat Conservation
2105 Osuna Road NE
Albuquerque, New Mexico 87113-1001
Telephone: (505) 346-2525
E-mail: r2esweb@fws.gov
http://ifws2es.fws.gov/

Reference

U.S. Fish and Wildlife Service. 23 September 1993. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for the Plant Pima Pineapple Cactus (Coryphantha scheeri var. robustispina )." Federal Register 58 (183): 49875-49879.