National Collection of Imperiled Plants

CPC National Collection Plant Profile

Photographer:

Jane Villa-Lobos

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CPC National Collection Plant Profile

Pediocactus knowltonii

Family:	Cactaceae
Common Names:	Knowlton's Miniature Cactus, Knowlton's Pincushion Cactus
Author:	L. Benson
Growth Habit:	Shrub
CPC Number:	3131

Distribution
Protection
Conservation
References

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Photographer: Jane Villa-Lobos
Image Owner: Smithsonian Institution, Department of Systematic Biology, Botany

Pediocactus knowltonii is Fully Sponsored

Primary custodian for this plant in the CPC National Collection of Endangered Plants is:

Denver Botanic Gardens

Laura Smith contributed to this Plant Profile.

Pediocactus knowltonii

Pediocactus knowltonii L. Benson, Knowlton�s cactus, is a critically imperiled species with a single known viable population in New Mexico and adjacent Colorado. It is a Federally listed species as of 1979.

Pediocactus knowltonii is small, about the size of a penny, with large white flowers that bloom from April to early May. When not in flower the plant is extremely inconspicuous.

Distribution & Occurrence

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State Range

Colorado
New Mexico

Habitat

Pediocactus knowltonii is mainly found on slopes or hills in dry pinyon-juniper and sagebrush woodlands at 1800-2000m elevation. The soil usually consists of gravelly, dark, and sandy loams formed from tertiary alluvial deposits.

Distribution

This species is mainly restricted to San Juan County in New Mexico, but may also be present in adjacent La Plata County, Colorado.

Number Left

Cactus collectors nearly drove this species to extinction in the first two decades after its discovery. 100,000 plants were recorded in 1958 and only 100 plants were found in 1978. Subsequent protection of that population by The Nature Conservancy allowed the population to grow to 9,000 individuals in1986.

Protection

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Global Rank:	G1	1/12/2006	Guide to Global Ranks
Federal Status:	LE	10/29/1979	Guide to Federal Status
Recovery Plan:	Yes	3/29/1985

State/Area Protection

	State/Area	Rank	Status	Date
	New Mexico	S1	Critically Imperiled

Conservation, Ecology & Research

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Ecological Relationships

Unknown

Threats

The main threat to Pediocactus knowltonii is collection, as its rarity makes it very popular among cacti collectors. Additionally, its habitat is threatened by off-road vehicles, oil and gas exploration and development, and livestock grazing around the remaining population.

Current Research Summary

Unknown

Current Management Summary

The main population is on land owned and managed by The Nature Conservancy. Two reintroduction sites were selected in 1985 nearby the main population in San Juan County, New Mexico. Transplant survival and flowering at these sites have been good, but natural recruitment has been slow. Seeding trials have not resulted in new recruitment (Sivinski and McDonald).

Research Management Needs

Not Available

Monitoring Efforts

Pediocactus knowltonii is a tracked Colorado Natural Heritage Program species.

Ex Situ Needs

Not Available

References

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Books (Sections)

Cully, A. 1996. Knowlton's Cactus (Pediocactus knowltonii) Reintroduction. In: Falk, D.A., C.I. Miller, and M. Olwell, editor. Restoring Diversity, Strategies for reintroduction of endangered plants. Island Press. Washington D.C.

Electronic Sources

Colorado Natural Heritage Program. (2008). Master Plant List. [Website]. http://www.cnhp.colostate.edu. Accessed: 13 October 2008.

NatureServe. (2008). NatureServe Explorer: An online encyclopedia of life [web application]. [Internet].Version 7.0. NatureServe, Arlington, Virginia. http://www.natureserve.org/explorer. Accessed: (June 17, 2008).

Reports

Sivinski, R.C.; McDonald, C. Accessed 2008. Knowlton's Cactus (Pediocactus knowltonii): Eighteen Years of Monitoring and Recovery Actions. United States Forest Service. Online at http://www.fs.fed.us/rm/pubs/rmrs_p048/rmrs_p048_098_107.pdf.

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This profile was updated on 3/4/2010