Scientific Name: Hibiscus trionum
Also known as: Flower-of-an-hour
Venice mallow is a summer annual. It was introduced from Europe where it was grown as an ornamental. Venice mallow has an upright growth habit and can reach 10- to 18-inches in height. The stems are erect, covered with hairs and branch from the base. The leaves are deeply cleft into 3 to 5 coarsely toothed lobes and form on long petioles. The lower stems and petioles can be a red to purple in color. Venice mallow has a fibrous root system with a weak taproot. The flower of Venice mallow is very showy and are a light sulfur-yellow color with a deep red to purple center. Venice mallow is nicknamed "flower-of-an-hour" because flowers will only last several hours before the petals drop. Venice mallow spreads by seed. The seeds can lay dormant for up to 50 years. Venice mallow is found throughout United States.
Venice mallow can infest nurseries, orchards, gardens, roadsides, cultivated fields and open waste areas. Venice mallow tolerates drought and gravely soils. It is also noted to tolerate alkaline soils. Due to longevity of the seeds, it is crucial to mow or remove the plants prior to flowering and seed development. Following good agronomic practices such as watering and mowing will help to prevent infestations of Venice mallow.
For optimum control make your post-emergence herbicide application in the late spring when Venice mallow is young and actively growing.