Siphocranion macranthum (Hook. fil.) C. Y. Wu

A medicinal herb.

Stems prostrate-ascending, 20-70 cm, densely spreading villous to glandular floccose-villous, sometimes subglabrous. Petiole 0.5-3 cm; leaf blade ovate-lanceolate to ovate, (1-)3-10 × (1-)2.5-5 cm, puberulent on veins, adaxially sparsely appressed minutely hispid, abaxially subglabrous, base broadly cuneate, margin coarsely remote serrate, apex acute. Racemes 4-20 cm; bracteoles lanceolate, 4-10 mm, ciliate. Pedicel ca. 5 mm. Calyx ca. 4 mm, glandular puberulent; upper lip ca. 3 mm, teeth triangular, apex mucronate; lower lip ca. 2.5 mm, teeth narrowly triangular, subulate; fruiting calyx conspicuously veined, declinate, to 1.2 cm; teeth of upper lip to 4 mm, teeth of lower lip narrow lanceolate, ca. 2 mm. Corolla reddish to purplish blue, tubular, to 2.5 cm, ± straight, throat slightly dilated; upper lobes ovate, subequal, ca. 3 mm; lower lip 4-9 mm, subcircular, slightly concave, margin entire. Stamens included, anterior 2 inserted on or near throat of corolla. Nutlets yellow-brown, ovoid, ca. 1.5 mm wide. Fl. Jul-Oct, fr. Oct-Nov.

Guangxi, Guizhou, Sichuan, Xizang, Yunnan [India, Myanmar, Vietnam]

Subtropical evergreen and mixed forests; 1300-3200 m.

Plectranthus macranthus J. D. Hooker, Fl. Brit. India 4: 616. 1885; Hancea hemsleyana H. Léveillé; H. prainiana H. Léveillé; Isodon macranthus (J. D. Hooker) Kudo; P. prainiana (H. Léveillé) Kudo; Rabdosia macrantha (J. D. Hooker) H. Hara; S. macranthum var. microphyllum C. Y. Wu; S. macranthum var. prainianum (H. Léveillé) C. Y. Wu & H. W. Li.

Siphocranion macranthum is a species of flowering plant in the family Lamiaceae. It is commonly known as big-flower siphocranion and tong guan hua in China. It is a perennial herb that is native to Assam, Myanmar, Tibet, Vietnam, South China and East Himalayas. S. macranthum grows in subtropical evergreen and mixed forests.