Semi-desert, foothills. Openings. Summer.
San Juan National Forest above Dolores River, May 8, 2009.

This lovely, symmetrical ball of spines is fairly common from Sagebrush areas to the upper limits of Pinyon/Juniper forests.  Flowers are white, pink, yellow, or green.  Spines are smooth, radial spines are white, and the central spine(s) is brown to black.  The plant shown at left is about six inches tall and seven inches wide, quite a large Pediocactus simpsonii.  This cactus is found in Nevada, Wyoming, and all Four Corners states, although it is rare in Arizona.  

The plant was first collected for science in Nevada by J. H. Simpson who made a number of western exploratory expeditions as a Topographical Engineer.  Simpson must have given the plant to George Engelmann, an eminent botanist and cactus expert, to examine.  Engelmann recognized the plant as a new species and named it Echinocactus simpsonii in 1863.  In 1913 Nathaniel Britton and Joseph Rose created a new genus, Pediocactus, and placed this plant in it.  (More biographical information.)

"Pedio" means "plains".

Semi-desert, foothills. Openings. Summer.
San Juan National Forest above Dolores River, May 8, 2009 and Price's Farm, May 8, 2010.

The top two photographs at left show plants about four inches tall; the bottom plant is just an inch and a half tall.

Semi-desert, foothills. Openings. Summer.
San Juan National Forest above Dolores River, May 8, 2009.

Here you can see the brown central vertical spines and the mostly white radial spines.

Semi-desert, foothills. Openings. Summer.
Northeast Arizona Navajo Reservation, June 3, 2006.

As the photographs on this page indicate, the appearance of Pediocactus simpsonii varies considerably depending on the closeness of the tubercles (the green, almost pyramid-shaped bumps) and the length of the spines.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Pediocactus simpsonii