Japan Flora: Rhizomes elongate, usually terminated by a tuber; culms terete, 40-80 cm. long, 2-5 mm. thick, glaucous-green, smooth, septate- nodose within, the sheaths 5-20 cm. long, frequendy partially reddish; spikelets cylindric, 4 cm. long, 3-4 mm. thick; scales broadly elliptic, 5-6 mm. long; achenes obovate-orbicular, 2 mm. long, tawny, lustrous, smooth, the brisdes with short spines at tip, the spinulae shorter toward apex, the style-base short-deltoid, with a strongly depressed inconspicuous basal disc. July-Oct. Shallow water.

Honshu (s. part of Kinki Distr.), Kyushu; rare. Ryukyus, Formosa, China, India, and Malaysia.