Peebles Navajo Cactus
Peebles Navajo Cactus
Pediocactus peeblesianus var.peeblesianus
|Listed||October 26, 1979|
|Description||Small, spherical cactus, with yellowish flowers.|
|Habitat||Navajoan Desert; gravelly soils on slopes and hilltops.|
|Threats||Quarrying, residential development, collectors.|
Peebles Navajo cactus—Pediocactus peeblesianus var. peeblesianus, also known as the Navajo plains cactus—is small and spherical. It usually grows as a single stem, which is up to 1 in (2.5 cm) tall and 0.75 in (2 cm) in diameter. The four radial spines of each cluster (areole) grow in the form of a twisted cross; central spines are absent. Yellow to yellow-green flowers appear in the spring and are often larger than the stem itself. During dry weather, stems retract into the ground and are difficult to locate. Seedlings germinate August through October and are typically found very close to the base of the parent plant. The genus for this cactus has also been given as Echinocactus, Navajoa, Toumeya, and Utahia.
This cactus grows on sunny slopes and flat hilltops in well-drained, gravelly soils derived from Shinarump conglomerate (Chinle Formation). The preferred soils are found in a strip about 1 mi (1.6 km) wide and 7 mi (11 km) long, running from southeast to northwest across the hills north of Holbrook, Arizona. Habitat elevation is between 5,400 and 5,600 ft (1,645 and 1,710 m).
Surrounding vegetation is open and sparse, consisting of low shrubs, grasses, and annuals of the Navajoan Desert community: snakeweed, shad-scale, four-winged saltbush, rabbitbrush, sagebrush, Mormon tea, Galleta, beehive cactus, Whipple devil claw, and Opuntia.
Peebles Navajo cactus is found only in Navajo County in the area around Joseph City and Holbrook. In 1987, five known populations were estimated to contain a total of about 1,000 plants. Two populations are on U. S. Bureau of Land Management (BLM) land; the three others are on private land. The welfare of populations on public lands is given a high priority in the most recent BLM management plans.
Over the years, much of the suitable habitat for this cactus has been destroyed by gravel quarrying, which has worked the seam of gravels the cactus prefers. During the late twentieth century, suburbs of Holbrook have expanded into the surrounding hills. Remaining cactus habitat is considered prime land for residential development.
Illegal collection is a serious threat to this cactus. Because pediocacti are difficult to cultivate, commercial dealers prefer to collect wild plants.
Conservation and Recovery
Peebles cactus is on the Arizona State Protected list as Toumeya peeblesiana and cannot be legally collected without a permit. In 1983 it was listed as a rare species by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Under this treaty, any import or export of the cactus requires a permit. Enforcement of treaty prohibitions, however, is difficult.
Monitoring plots were established in 1980 and are examined yearly to evaluate the growth and reproductive potential of the cacti. An intensive survey, conducted in 1987, noted many seedlings at known sites but found no new populations.
Benson, L. 1962. "A Revision and Amplification ofPediocactus, III and IV." Cactus and Succulent Journal of America 34 (57-61): 163-168.
Heil, K., B. Armstrong, and D. Schleser. 1981. "AReview of the Genus Pediocactus. " Cactus and Succulent Journal of America 53: 17-39.
U. S. Fish and Wildlife Service. 1987. "Endangered and Threatened Species of Arizona and New Mexico (with 1988 Addendum)." U. S. Fish and Wildlife Service, Albuquerque.
U. S. Fish and Wildlife Service. 1984. "Peebles Navajo Cactus (Pediocactus peeblesianus (Croizat) L. Benson var. peeblesianus ) Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.