VENICE MALLOW, Hibiscus trionum L. 1, entire plant; 2, flower; 3, open seed pod with a seed; 4, mature seed pod with sepals. Annual, reproducing by seed. Stems erect or spreading, hairy, 8 to 20 inches (20 to 50 cm) tall. Root system fibrous. Leaves alternate, irregularly shaped, with 3 to 7 parts. Flowers 1 to 2 inches (2.5 to 5 cm) in diameter, with 5 petals, pale yellow or whitish with a purplish-black center. Petals often have a purple margin. Each flower remains open for only a few hours. Seed pod hairy, containing many seeds. Seeds grayish-black, kidney-shaped, rough, about 1/16 inch (1.5 mm) long. Found in gardens, cultivated fields, and waste places. Especially serious in cultivated crops after the last cultivation. Also commonly known as flower-of-an-hour.