Japan Flora: Resembles the preceding; spike­lets cylindric, 2-4 cm. long, 3-4 mm. thick, pale green; scales narrowly oblong, obtuse, 6-8 mm. long; achenes 2 mm. long, very abruptly contracted at apex and with a prominent apical discoid tubercle, the brisdes spinulose at tip, with spinulae longer toward the apex; anther connective with a linear mucro at apex.  July-Oct. Ponds and ditches.

Honshu (Kanto, Hokuriku Distr. and westw.), Shikoku, Kyushu. Korea