Oenothera elata is our most common upper elevation Evening Primrose [in the Gila Wilderness, New Mexico], just as Oenothera caespitosa is our most common lower elevation one. Oenothera elata is usually single stemmed and stands strongly erect. The petals are yellow turning orange with age. The stem is reddish. The leaves are lanceolate and sessile. Oenothera elata is commonly seen at the roadside at upper elevations. The seeds are irregularly shaped and stacked in the capsules. The capsules when mature are woody, brown and have four chambers each with two rows of small angled seeds.