Description from Flora of China
Herbs annual or biennial. Stems erect, to 70 cm, spreading hirsute, retrorse gray pilose. Petiole 0.5-2 cm; leaf blade ovate to triangular-ovate, 2-5 × 1.5-4 cm, abaxially gray minutely tomentose, base cordate to subtruncate, margin serrate or obtusely serrate, apex acute. Inflorescences densely, retrorse fine white pilose; verticillasters 4- to many flowered, widely spaced, in terminal racemes; bracts ovate, longer than pedicels, margin ciliate. Pedicel 2-3 mm. Calyx tubular-campanulate, 7-9 mm, finely pilose, puberulent, intermixed with yellowish glands; upper lip ovate, ca. 2.5 × 3 mm, ciliolate, apex mucronate; lower lip nearly as long as upper, deeply 2-toothed. Corolla scarlet or deep red, 2-2.3 cm, pubescent; tube ca. 1.6 cm; upper lip shorter than lower; lower lip ca. 7 × 8.5 mm. Stamens exserted; filaments ca. 4 mm; connectives ca. 1.5 mm, slender. Nutlets yellow-brown with blackish spots, obovoid, 1.5-2.5 mm. Fl. Apr-Jul.
Used as an ornamental and medicinally.
Cultivated in China and naturalized in Yunnan [South America]