Plectranthus macrocalyx Dunn, Notes Roy. Bot. Gard. Edinburgh 8: 157. 1913; Amethystanthus taiwanensis Masamune; Isodon bifidocalyx (Dunn) H. Hara; P. bifidocalyx Dunn; P. drosocarpus Handel-Mazzetti; Rabdosia bifidocalyx (Dunn) H. Hara; R. macrocalyx (Dunn) H. Hara; R. taiwanensis (Masamune) H. Hara.

Herbs perennial. Stems numerous, erect, 40-100(-150) cm, appressed pubescent. Petiole (0.5-)2-3(-6.5) cm; leaf blade ovate, (5-)7-10(-15) × (2-)2.5-5(-8.5) cm, papery, subglabrous, appressed pubescent on veins, base attenuate-decurrent, margin crenate-serrate, apex long acuminate. Racemes terminal and axillary, narrow, 6-10(-15) × ca. 2.5 cm; cymes pedunculate, (1-)3-5-flowered, together forming a pointed panicle; floral leaves subsessile, ovate. Pedicel 2-4 mm. Calyx broadly campanulate, ca. 2.7 × to 3 mm, pubescent, 2-lipped; teeth triangular, lower 2 slightly larger, apex acute; fruiting calyx dilated to 6 mm, obviously 2-lipped. Corolla purplish to purple-red, ca. 8 mm, sparsely puberulent, glandular, tube ca. 4 mm, upper lip ca. 2 mm, lower lip ca. 4 mm. Stamens and style slightly exserted. Nutlets brown, ovoid, ca. 1.5 mm, glabrous. Fl. Jul-Aug, fr. Sep-Oct.

* Thickets and forests on slopes; 600-1700 m. Anhui, Fujian, Guangdong, Guangxi, Hunan, Jiangsu, Jiangxi, Taiwan, Zhejiang.