The tiny stems of Brady's pincushion cactus, pediocactus bradyi
, are at most 2 inches across, and may be single or (less often) form clusters of up to 12. Stems are spherical in shape but flattened and shrunken at some times of year, when they barely rise above the surrounding soil and are hard to spot even when close up. The very short, white or yellowish spines are (usually) all radial, numbering between 13 and 16, and angled back towards the stem surface; occasionally 1 or 2 darker-colored central spines might be present. The pale yellow flowers and green/brown fruit are also small, about one inch and half an inch in diameter respectively.
The plant grows in a 25 mile long strip of land either side of the Colorado River (Marble Canyon) in north Arizona, south of Lees Ferry. It is endangered, and monitoring studies suggest that populations are declining.