Description from Flora of China
Herbs suffruticose, to 90 cm tall. Petiole 3-4.5 cm, glabrous; leaf blade ovate to triangular-ovate, 2.5-7 × 2-4.5 cm, glabrous, abaxially glandular, base truncate or ± rounded, margin serrate, apex acuminate. Verticillasters 2-6-flowered, in racemes to 20 cm; bracts ovate, red, enveloping flowers in bud, apex caudate-acuminate. Pedicel 4-7 mm, red glandular villous. Calyx red, campanulate, ca. 1.6 cm in flower, dilated to 2 cm after anthesis, red glandular, veins villous, 2-lipped to ca. 1/3 its length; upper lip triangular-ovate, 5-6 × 10 mm, apex mucronate; lower lip slightly longer than upper, deeply 2-toothed, teeth triangular. Corolla scarlet, 4-4.2 cm, pubescent; tube slightly dilated at throat; upper lip straight, somewhat concave, oblong, 8-9 × ca. 4 mm; lower lip shorter than upper. Filaments ca. 5 mm; connectives ca. 1.3 cm. Nutlets dark brown, ellipsoid, ca. 3.5 mm, apex irregularly pleated, margin (or midvein) narrowly winged. Fl. Mar-Oct.
The corolla is purple or even white in different varieties.
Cultivated in China [South America]