Pediocactus knowltonii L. Benson
Family: Cactaceae
Knowlton's cactus
[Pediocactus simpsonii var. knowltonii (L.D. Benson) Halda]
Pediocactus knowltonii image
Robert Sivinski  
Plants branched or unbranched. Stems globular to short cylindric, 0.7-5.5 × 1-3 cm; areoles circular, villous. Spines smooth, relatively hard, all radial, mostly 18-26 per areole, spreading, recurved, or somewhat pectinate, reddish tan, pink, or white, 1-1.5 mm, canescent. Flowers 1-3.5 × 1-2.5 cm; scales and outer tepals essentially entire, often undulate; outer tepals with brownish midstripes to 1.5 mm wide, 4-17 × 4-6 mm; inner tepals pink, oblanceolate, 8-25 × 3-8 mm. Fruits green, drying reddish tan, turbinate,4 × 3 mm. Seeds black, 1.5 × 1-1.2 mm, papillate but not rugose. Flowering spring. Gravel pavements in pinyon-juniper woodlands with mixed sagebrush; of conservation concern; 2000 m; N.Mex. Pediocactus knowltonii is the smallest and rarest member of the genus. The species is very closely related to P. simpsonii; chloroplast DNA sequence analysis provides support that it represents a recent developmental mutation within P. simpsonii (J. M. Porter et al. unpubl.).

Pediocactus knowltonii image
Robert Sivinski  
Pediocactus knowltonii image
Robert Sivinski  
The National Science Foundation
This project made possible by National Science Foundation Award 1410069