Japan Flora: Perennial herb, rhizomatous and stoloniferous; stems terete, erect, 40-80 cm. long, simple or sparsely branched, minutely glandular- pubcrulent on upper part; leaves opposite, rarely verticillate in 3’s or 4’s，lanceolate to narrowly ovate, 4-12 cm. long, 1-4 cm. wide, acuminate, acute to subobtuse at base, sessile, entire, deep green, often whitish beneath, black-spottcd; flowers in a many-flowered terminal leafy panicle or in whorls in the upper axils, the pedicels 7-12 mm. long, bracteate; flowers yellow, 12-15 mm. across; calyx-segments narrowly ovate-deltoid, acuminate，with a line of black glands near margin; corolla­lobes narrowly ovate, granular-papillose inside; capsules glo­bose, about 4 mm. in diameter; style persistent, 5-6 mm. long. July-Aug. Wet places.

Hokkaido, Honshu, Kyushu (mountains). Temperate regions of e. Asia.