Nichol's Turk's Head Cactus

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Nichol's Turk's Head Cactus

Echinocactus horizonthalonius var. nicholii

ListedOctober 26, 1979
FamilyCactaceae (Cactus)
DescriptionEight-ribbed barrel cactus with a single blue-green stem and pink or purplish flowers.
HabitatSonoran Desert; in full sun on limestone talus slopes.
ThreatsCollectors, quarrying, off-road vehicles.
RangeArizona; Sonora, Mexico


Nichol's turk's head cactus, Echinocactus horizon-thalonius var. nicholii, is an eight-ribbed barrel cactus, reaching a maximum height of 20 in (50 cm) and a diameter of 8 in (20 cm). The blue-green stem bears spines on vertical, spiraling ridges. Each spine cluster (areole) contains three central and five radial spines. Bright pink or purplish flowers bloom from April to mid-May. Fruits are covered with white, woolly hairs. The plant always grows as a single stem, but because seedlings often grow around its base, it may appear to have multiple stems.

Population dynamics are slow and the turnover rate is low. The mean age of this cactus is nine and one-half to more than 13 years and maximum age varies from 24-39 years.


Nichol's turk's head cactus is found within the Arizona Upland Subdivision of Sonoron Desert scrub at an elevation between 3,281 and 3,829 ft (1,000 and 1,167 m). Preferred sites are in full sun on limestone talus slopes in soils rich in calcium carbonate. Surrounding vegetation is characterized by sparse trees and scattered low shrubs dominated by foothill palo verde, triangle leaf bursage, white ratany, and prickly pear cactus. The semiarid habitat receives less than 13 in (33 cm) of annual rainfall. Freezing temperatures occur only about five nights per winter.

There are differences in fecundity and survival rates for plants in rocky terrace versus alluvial habitats. Populations are denser at the higher sites where there is more moisture and rocks. In the alluvial habitat, plants grow in open, exposed areas containing few plants in the shrub-tree strata. Shaded plants grow, flower, and survive at lower rates than plants in the open. Soil erosion is an important factor; half-buried plants do not grow well and rodents eat plants that have washed out or been injured.


Nichol's turk's head cactus is endemic to the Sonoran Desert of southern Arizona and adjacent Mexico. Its estimated potential habitat in the Waterman Mountains is 5,000 acres (2,025 hectares). The Vekol Mountains add another 5,700 acres (2,305 hectares) of suitable habitat.

Populations of the cactus are grouped at two locations in south-central Arizona: the Waterman Mountains (north-central Pima County); and the Vekol Mountains (southwestern Pinal County). One small population has been found in northwestern Mexico in Sierra del Viejo (in the state of Sonora). In 1983, U. S. Bureau of Land Management (BLM) personnel surveyed a population on the north side of Waterman Peak that numbered 1,179 cacti. There are no current population estimates for other sites.


Nichol's turk's head cactus is threatened primarily by collectors. Between 1982 and 1984, this cactus was advertised for sale in 11 different plant catalogs, two of which specified field-collected plants. At least one nursery is known to collect seeds from the cactus in the wild, a practice that damages the plant and inhibits propagation.

Limestone quarrying eliminated a small population near the Happy Jack Mine in the Waterman Mountains, and roads leading to this quarry cut through several other colonies. Recreational off-road vehicles have damaged habitat and destroyed plants. Hunters sometimes use cacti for target practice.

Conservation and Recovery

This cactus is on the Arizona state protected list (Arizona Native Plant Law), which prohibits collecting except by permit. In 1983 the species was given a CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) classification that requires a permit for importing or exporting the cactus. More strict enforcement of the Lacey Act, which makes it illegal to buy or sell any plant taken or possessed in violation of any law, will be needed to deter collectors.

Since many populations of this cactus are on lands managed by the BLM and the Bureau of Indian Affairs (BIA), proper management and regulation of mining operations and claim surveys will do much to preserve remaining Nichol's turk's head cactus populations. The recovery plan recommends that the BLM withdraw all suitable, unclaimed habitat from any future mining activities; consolidate federal agencies that manage the lands; develop off-road vehicle management; and coordinate with the BIA to monitor and manage populations on the Papago Reservation.


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


Benson, L. 1969. The Cacti of the United States and Canada. Stanford University Press, Stanford, Calif.

Fuller, D. 1985. "U.S. Cactus and Succulent BusinessMoves toward Propagation." Traffic (U.S.A.) 6 (2): 1-11.

U. S. Fish and Wildlife Service. 1979. "Determination that Nichol's Turk's Head Cactus (Echinocactus horizonthalonius var. nicholii ) Is an Endangered Species." Federal Register 44: 61927-61929.

U. S. Fish and Wildlife Service. 1986. "Recovery Plan for the Nichol's Turk's Head Cactus (Echinocactus horizonthalonius var. nicholii )." U. S. Fish and Wildlife Service, Albuquerque.

Weniger, D. 1970. Cacti of the Southwest. University of Texas Press, Austin. Press.