Oenothera triloba, with common namesstemless evening primrose and sessile evening primrose is a flowering plant in the primrose family. It is native to North America, where it is primarily found in northern Mexico and in the south-central United States. It is found in dry, open areas such as glades, prairies, and sometimes even lawns. It appears to respond positively to soil disturbance.
It is a winter annual that produces large yellow flowers in the spring. The flowers open near sunset.