狭叶黑三棱 xia ye hei san leng

Sparganium stenophyllum Maximowicz ex Meinshausen.

Stems erect, 20-36 cm tall, slender. Leaves 25-35 cm × 2-3 mm, upper flattened, lower keeled or trigonous on abaxial side. Panicles 7-15 cm, main axis consisting of 5-7 male heads and 2 or 3 female heads, usually with 1 lateral branch at base; lateral branch 5-8 cm, with 2 or 3 male and 1 or 2 female heads. Male flowers: perianth segments spatulate, ca. 2 mm, lobate at apex; filaments ca. 2 mm; anthers oblong, ca. 1 × 0.3 mm. Female flowers: perianth segments spatulate, ca. 2 mm, lobate at apex; ovary sessile; styles ca. 0.5 mm; stigmas unilateral, ca. 1.5 mm. Fruit obovoid, ca. 4 mm. Fl. and fr. Jun-Sep.

Shallow water of lakes, swamps, and streams. Hebei, Heilongjiang, Jilin, Liaoning [Japan, Korea, Russia].