, a shrub, forms much-branched clumps up to six feet tall and wide, and is found in a number of habitat types, over quite a wide geographical range, from northern Nevada to southeast Arizona and southern California. At least eight varieties are recognized, differing in such aspects as stem cross-section (smooth or grooved), hair characteristics, leaf shape, leaf dimensions and the arrangement of the involucres. The species is known informally as 'brain plant' owing to the cerebral-like appearance of its numerous short, linear, angled branch segments.
Flowering stem segments are short, at most 2 inches, and they have one (reddish, hairless) involucre at each node, usually with two flowers, attached by short, slender stalks. Tepals are most often white, sometimes reddish or pale yellow, and hairless. Stamens are exserted.