美国薄荷 mei guo bo he

Plants annual. Stems subglabrous, villous on nodes and at apex along angles, glabrescent. Petiole to 2.5 cm, nearly lacking apically, base slightly dilated; leaf blade ovate-lanceolate, to 10 × 4.5 cm, papery, adaxially villous or glabrescent, abaxially sparsely, impressed glandular, villous on veins, base rounded, margin unequally serrate, apex acuminate. Verticillasters in terminal capitula to 6 cm in diam.; bracts short petiolate, leaflike, margin entire, red, shorter than capitula; bracteoles linear-subulate, ca. 10 × 1.5 mm, long caudate, puberulent, red. Pedicel ca. 1 mm, puberulent. Calyx slightly curved, ca. 10 × 2.5 mm, purple-red when dry, veins pubescent, throat sparsely hirsute; teeth equal, subulate-triangular, ca. 1 mm, apex spinescent. Corolla purple-red, ca. 2.5 cm, puberulent; upper lip straight, slightly recurved outward, margin entire; lower lip spreading, with middle lobe narrower, emarginate. Fl. Jul.

Cultivated in China [North America].