Japan Flora: Smaller; radical leaves long-petioled, the blade broadly lanceo­late to deltoid-ovate, 3-7 cm. long, 1.5-3 cm. wide, rounded to shallowly cordate at base, subabruptly narrowed to an acute or obtuse apex, the cauline leaves on shorter petioles 3-10 cm. long; inflorescence much shorter than the leaves, one-sided, 3- to 7-flowered, abruptly deflexed at the base in fruit; flowers purplish blue, 1.5-2 cm. across; perianth-segments oblong; cap­sule ellipsoidal, about 10 mm. long; seeds ellipsoidal, about 1 mm. long, longitudinally ribbed and transversely lineolate.  Sept.-Oct. Common in paddy fields and shallow ponds in lowlands.

Honshu, Shikoku, Kyushu. Korea and China. se. Asia.