Mentha arvensis Linnaeus subsp. haplocalyx Briquet var. sachalinensis Briquet ex Miyabe & Miyake, Fl. Saghalin 361. 1916; M. arvensis var. piperascens Holmes; M. sachalinensis (Briquet) Kudo var. arguta Kitagawa.

Plants rhizomatous, perennial. Stems erect, 50-100 cm, striate, densely retrorse pubescent along angles, little branched. Petiole 0.5-1.5 cm; leaf blade elliptic-lanceolate, (2.5-)4-9 × 1-3.5 cm, glandular, ciliate, puberulent on veins, base attenuate, margin shallow serrate, apex acute. Verticillasters axillary, many flowered, globose, to 1.5 cm in diam., short pedunculate; floral leaves subsessile, sublanceolate; bracteoles linear to linear-lanceolate, 3-4 mm, ciliate. Pedicel ca. 2 mm, glabrous. Calyx campanulate, ca. 1.5 mm, densely pilose, yellow glandular, mouth and teeth pilose inside; teeth narrowly triangular, ca. 1.5 mm, apex acute. Corolla purplish or purplish red, ca. 4 mm, pilose; lobes ovate-oblong, upper emarginate. Anterior stamens slightly longer, ca. 5 mm. Nutlets yellow-brown, oblong, glabrous, ribbed. Fl. Jul-Aug, fr. Sep.

Wet grasslands near rivers, lakes; 200-1100 m. Heilongjiang, Jilin, Liaoning, Nei Mongol [Japan, Russia].