Japan Flora: Aquatic or hygrophytic summergreen perennial with brownish yellow appressed to ascending soft hairs while very young; rhizomes slender, long-creeping, 1.5-2 mm. in diameter; leaves radical, few, the petioles 5-15 cm. long; leaflets or pinnules 4, thinly chartaceous to membranous, sessile, deltoid-flabellate, 1-2 cm. long and as wide, broadly rounded at apex, broadly cuneate at base, entire, glabrous on upper surface; veins slender, nearly parallel, forked, somewhat anastomosing; pedicels short, 2-3- nate, connate, adnate to the base of stipe, erect; sporocarps soli­tary on a pedicel, ellipsoidal, 4-5 mm. long, densely pubescent at first, becoming glabrous, the basal tooth minute.   Sept.-Oct. Paddy fields and ponds.

Hokkaido, Honshu, Shikoku, Kyushu; common.  Europe to n. India and e. Asia, intro­duced in N. America.