Oenothera flava, the yellow evening primrose (a name it shares with Oenothera serrulata), is a species of flowering plant in the family Onagraceae.[1] It is native to western Canada (except British Columbia), the western and central United States, and Mexico (except southeastern Mexico), and it has been introduced to the former Czechoslovakia.[2] An almost stemless perennial reaching, it is typically found in damp situations such as prairie swales, open woodlands, and alongside streams.[1]