Shrubs, low, forming mats, 10-30 cm. Stem segments easily detached to firmly attached, green, flattened, narrowly to broadly obovate, 3.5-9 × 2.5-5 cm, low tuberculate, glabrous; areoles 4-6(-7) per diagonal row across midstem segment, oval, 3.5 × 2.5 mm; wool white. Spines in most areoles, straight, acicular, terete; major spines 0-1 per areole, reflexed to porrect (rarely ascending), gray-white to brown, (15-)25-40(-60) mm; intermediate spines 0-3, reflexed, 12-20 mm; minor spines 2-4, reflexed, yellow-gray, 3-6 mm. Glochids loosely packed, in small tuft or crescent at adaxial margin of areole, yellowish, inconspicuous, to 4 mm. Flowers: inner tepals yellow throughout, 30-45 mm; filaments white to red; anthers yellow; style white; stigma lobes green. Fruits rarely set, top-shaped to barrel-shaped, 15-20 × 15 mm, glabrous; areoles 10-15, most bearing 3-12 spines or distal spines bearing 1-3 spines. Seeds tan, large, 5-7 mm; girdle protruding 1-1.5 mm. 2n = 66. Flowering summer (late Jun-early Jul). Dark basaltic cliffs and derived sands; 100-800 m; B.C.; Idaho, Oreg., Wash.