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 collected 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.

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

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

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

The overall appearance of Pediocactus simpsonii changes considerably from tiny one or two inch balls of lacy appearing spines, to three-to-five inch balls of white fluff to the fully mature prickly looking plants shown at the top of this page.