Japan Flora: Rhi­zomes 8-12 mm. in diameter, creeping; leaves 50-80 cm. long, 6-15 mm. wide, flat, acuminate, smooth, deep green, ensiform, with a prominent raised midrib, scarcely narrowed below, the sheathes flattened laterally; peduncle leaflike, shorter than the leaves, slightly flattened; bract (spathe) leaflike, 20-40 cm. long, 5-8 mm. wide; spadix sessile, terete, cyliudric, densely flowered, 4-7 cm. long, 6-10 mm. thick, ascending, light yel­low; anthers light yellow, slightly longer than the perianth. May-Aug. Shallow water along rivers.

Hokkaido, Hon­shu, Shikoku, Kyushu. Siberia, e. Asia, N. America, and Europe (introduced).