Japan Flora: Stems elongate, floating or aerial, 30-50 cm. long, the floating leaves mostly narrow, about 4 mm. wide, compressed, keeled beneath; spikes simple; pistillate heads 2-4, 7-10 mm. in diameter, the lower 1 or 2 with a supra-axillary peduncle; staminate heads commonly approximate; fruit short-pedicelled, about 4 mm. long, fusiform; stigma linear, about 1 mm. long.
Reported from Hokkaido (Mount Yubari). Kamchatka, Europe, and N. America.