Pediocactus knowltonii

Pediocactus knowltonii

Pediocactus knowltonii L.D.Benson

One of the smallest members of the genus. Short, radially arranged spines shelter a stem whose diameter usually falls within a few centimetres. Natural sites are concentrated in northern New Mexico. The species has been the subject of long-term observations and population-restoration experiments. [Heil and Porter 2003a] [2-WWW] [Sivinski and McDonald 2007]

2 min readUpdated 11 October 2026

Name and small area of occurrence

POWO accepts Pediocactus knowltonii as native to northern New Mexico. Occurrence in Colorado is marked as doubtful. Older publications include P. bradyi var. knowltonii and P. simpsonii var. knowltonii. These are now synonyms of the separately accepted species. [2-WWW]

A short stem and radial spines

The stem is globose or shortly cylindrical, solitary or branched. The floristic description gives a height of 0.7–5.5 cm and a width of 1–3 cm. Each areole contains 18–26 very short spines, 1–1.5 mm long. They are radial, whitish, pinkish or light brown, often curved or arranged like the teeth of a comb. The pink flowers are 1–2.5 cm in diameter. The seeds are black and small, with a tuberculate coat. Plants flowering in spring occur on gravelly surfaces among junipers, pines and sagebrush, at about 2000 m above sea level. [Heil and Porter 2003a, Flora of North America, P. knowltonii]

Survival of transplanted plants and regeneration

In 2007, Sivinski and McDonald described eighteen years of monitoring and attempts to restore populations. The natural site known at the time occupied a hill covering about 10 ha. From 1985, 301 vegetatively propagated plants were introduced to two similar habitats. The transplanted specimens survived well and flowered, while new seedlings appeared slowly. The abstract thus distinguishes successful survival of introduced plants from the rate at which the next generation develops. [Sivinski and McDonald 2007, abstract of a chapter in conference proceedings]

Pediocactus bradyi. Contractile roots and population life Pediocactus in the landscape. Habitats, weather and population recruitment

Materials from the author's archive

Older descriptions and cultivation observations · Pediocactus knowltonii

Synonyms and names in the literature

Pediocactus bradyi var. knowltonii · Pediocactus simpsonii var. knowltonii [2-WWW]

Sources for this account

Book chapter2003aExcerpt consulted

Pediocactus

[Heil K. D., Porter J. M., Pediocactus, Flora of North America North of Mexico, Oxford University Press, 2003a, tom 4, s. 211–216]

A description of the genus and a species key, with separate accounts of stems, spines, flowers, fruits and seeds. It includes habitats, ranges and elevational ranges. Older treatments of rank and synonyms reflect the state of the 2003 account.

GenusDistributionPhysiology and anatomyPediocactus

Article or source page ↗

[2-WWW]Source website

Plants of the World Online — Royal Botanic Gardens, Kew

https://powo.science.kew.org/

Accepted names, synonyms and distribution. A citation beside a taxon leads to its record.

Accessed 2026-10-08.

Book chapter2007Abstract consulted

Knowlton’s cactus (Pediocactus knowltonii): Eighteen years of monitoring and recovery actions

[Sivinski R. C., McDonald C., Knowlton’s cactus (Pediocactus knowltonii): Eighteen years of monitoring and recovery actions, Southwestern rare and endangered plants: Proceedings of the Fourth Conference; March 22–26, 2004; Las Cruces, New Mexico, USDA Forest Service, Rocky Mountain Research Station, Fort Collins, Colorado, 2007, s. 98–107, seria Proceedings RMRS-P-48CD]

Multi-year monitoring of Pediocactus knowltonii and population restoration measures. The authors describe the fates of vegetatively propagated plants transplanted into similar habitats and the slow emergence of a new generation from seeds.