Arizona and south California
Washes, stony hillsides, desert flats, up to 4,000 feet
Ovate, entire edges, about a third of an inch long, on short stalks
Stems of euphorbia melanadenia are deep red in color and much branched, bearing small, green, ovate, oppositely-arranged leaves which often have red edges. Leaves have a pair of small stipules at the attachment point, and a light covering of tomentose hairs, lying flat against the surface. Hairs tend to fall away on older leaves. Plants form tangled, low-growing clusters, spreading mostly sideways.
The inflorescence consists of a bell-shaped involucre formed of five fused bracts, also with a tomentose hair covering, which supports five petal-like appendages, white towards the tips, with a red nectar gland at the base. The red and white parts are approximately equal in width. Appendage tips have one or two notches. At the center are a ring (15 to 20) of tiny staminate florets surrounding an equally small pistillate floret.