白头马蓝 bai tou ma lan

Pyrrothrix heterochroa (Handel-Mazzetti) C. Y. Wu & C. C. Hu; Strobilanthes heterochroa Handel-Mazzetti; S. leucocephala Craib; Tetragoga angustiphylla Q. H. Chen; T. esquirolii (H. Léveillé) E. Hossain.

Subshrubs 0.5-2 m tall, much branched, anisophyllous. Stems 4-angled, basally glabrescent, apically rust-colored retrorsely setose. Petiole 1-3 cm, hispid-pilose; leaf blade ovate-elliptic to oblong-elliptic, 4-17 × 2-8 cm, smaller of pair ca. 3/4 size of larger one, roughly hirsute, abaxially paler, adaxially with prominent cystoliths, secondary veins 7-10 on each side of midvein, abaxially prominent, and adaxially impressed, base cuneate and attenuate, margin serrulate and ciliate, apex acute to caudate. Inflorescences terminal, heads, often yellowish, 2-3 × ca. 2 cm, 8-10-flowered; rachis densely white sericeous with gland-tipped trichomes; bracts oblong-lanceolate, 1-3 × 0.5-0.7 cm, outer ones longer with caudate tips giving inflorescences an eared appearance, inner ones smaller, indumentum variable, white sericeous, with gland-tipped or non-glandular trichomes, and apically often becoming brownish; bracteoles oblanceolate, 7-9 × ca. 2 mm, abaxially basally white sericeous, trichomes apically often slightly rust-colored. Flowers imbricate on rachis. Calyx 7-10 mm, 5-lobed almost to base; lobes linear-oblanceolate, densely white sericeous toward base but slightly rust-colored toward apex, apex acute. Corolla violet, 3-3.5 cm, curved, ventricose, outside densely white pilose, inside glabrous except for trichomes retaining style; tube basally cylindric and ca. 4 mm wide for ca. 6 mm then gradually widened to ca. 1 cm at mouth; lobes ovate, ca. 4 × 5 mm, apex obtuse. Stamens 4, included; shorter filament pair ca. 4 mm, glabrous; longer filament pair ca. 7 mm, white pilose; anther thecae oblong, ca. 3 × 1 mm; pollen type 3. Ovary densely white pilose; style ca. 2.8 cm, white pilose. Capsule oblong, 7-10 mm, apically white pilose, 4-seeded. Seeds ovate in outline, ca. 3.5 × 2 mm, densely pubescent; areola small. Fl. Sep-Dec.

Mountain slopes; 200-800 m. Guizhou, Yunnan [Laos, Thailand, Vietnam].