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.
Oenothera biennis has a life span of two years (biennial) growing to 30â150 cm (12â59 in) tall. The leaves are lanceolate, 5â20 cm (2â8 in) long and 1â2.5 cm (1â2â1 in) broad, produced in a tight rosette the first year, and spirally on a stem the second year. Blooming lasts from late spring to late summer. The flowers are hermaphrodite, produced on a tall spike and only last until the following noon. They open visibly fast every evening producing an interesting spectacle, hence the name "evening primrose." The blooms are yellow, 2.5â5 cm (1â2 in) diameter, with four bilobed petals. The flower structure has an invisible to the naked eye bright nectar guide pattern. This pattern is apparent under ultraviolet light and visible to its pollinators, moths, butterflies, and bees. it can be invasive in eastern and central North America.
