Red-stalked evening primrose

Oenothera biennis (common evening-primrose, evening star, sundrop, weedy evening primrose, German rampion, hog weed, King's cure-all, or fever-plant.) is a species of Oenothera native to eastern and central North America, from Newfoundland west to Alberta, southeast to Florida, and southwest to Texas, and widely naturalized elsewhere in temperate and subtropical regions. Evening primrose oil is produced from the plant.