Common Aldrovanda

Stem 6-15 cm. Leaf whorls 1-2 cm in diam., 6-9-leaved; leaves yellowish green to green; petiole 3-6 × ca. 1.8 mm, apex with 4-8 bristles, bristles 5-7 mm, extending slightly beyond leaf blade; leaf blade segments reniform-orbicular, concave, 2-6 × 6-10 mm, forming a trap with segments rising upward on stimulation then closing together and narrowing, becoming elliptic or elliptic-oblong, 3-4 mm. Petals oblong, 3-4 × ca. 2.5 mm. Ovary 2-2.5 mm in diam.; placentas 5, parietal; ovules 2. Seeds 6-8, black. 2n = 38, 48.

Lakes, swamps, still waters of rivers, ditches. Heilongjiang, Nei Mongol [Africa (including Madagascar), E, N, and SE Asia, C and S Europe, N Pacific Islands].