Japan Flora: Stems erect, 40-70 cm. long; leaves flat, keeled beneath, suberect, as long as or slightly longer than the spikes, 4-10 mm. wide; spikes simple, more or less distant, the bracts usually longer than the spike; pistillate heads 3 or 4, 1.5-2 cm. in diameter in fruit, the lower 1 or 2 heads usually peduncled, the staminate 5-10; fruit oblong-fusiform, about 5 mm. long, 1.5-2 mm. across, not angled, with a slight constriction in tlie middle, narrowed toward both ends, the pedicels about 2 mm. long; style including the linear stigma, about 2 mm. long. July-Aug. Shallow water in lowlands.

Honshu, Kyushu. Korea.