Japan Flora: Nearly glabrous green annual; stem creeping and branching below, ascending above, 15-50 cm. long; leaves soft but rather thick, ovate-lanceolate, abruptly acute at apex, subabruptly narrowed below to a membranous sheath with long-pubescent mouth, 5-7 cm. long, 1-2.5 cm. wide, glabrous; spathe broadly cordate, rounded or with a short cusp at apex, nearly 2 cm. long, gla­brous or loosely pubescent outside; flowers blue, about 12 mm. across, the 2 lateral petals large and orbicular, clawed at base, the central one small and usually white.  June-Sept. Rather common in partly shaded grassy places, cultivated fields, and roadsides in lowlands and hills.

Hokkaido, Honshu, Shikoku, Kyushu. Sakhalin, Ussuri, Korea, Manchuria, China to Siberia, and the Caucasus.

var. ludens (Miq.) C. B. Clarke. Leaves narrow, puberulent beneath; spathe also more or less narrow and puberulent. Mountainous districts.

cv. Hortensis. A cultivated phase with large showy flowers yielding a blue dye from the corolla.