Like the long, lance-shaped leaves, the reddish brown stems of oenothera villosa
are hairy, and grow vertically, to a height of 5 feet. Stems may branch a few times, or remain unbranched. Leaves usually have indistinct teeth along the edges, and a distinctly reddish or whitish vein along the middle (most visible on the lower surface).
Flowers form in small clusters at the top of the stem and the upper leaf axils; they consist of four green or reddish sepals, around half an inch long, and four yellow to pale orange petals, obovate in shape and notched at the tip, centered on eight stamens and a four-parted style. Petals are about one inch in length.