城口马蓝 cheng kou ma lan

Pteracanthus flexus (Benoist) C. Y. Wu & C. C. Hu.

Herbs to 60 cm tall, isophyllous. Stems 4-angled, glabrescent. Petiole 1-5 cm, thinly pubescent; leaf blade ovate to elliptic, 3.5-15 × 3-7 cm, both surfaces glabrous except basally on abaxial midvein, cystoliths apparently absent, secondary veins 6-8 on each side of midvein, base cuneate and decurrent onto petiole, margin coarsely dentate or serrate, apex acute. Inflorescences axillary or terminal, spikes, 3-6 cm, lax, sometimes reduced to a single flower in axil of apical leaves; rachis gland-tipped pilose; bracts leaflike, oblong-oblanceolate, 1.5-2 × 0.2-0.4 cm, apically diminishing in size, gland-tipped pubescent, apex acute to acuminate; bracteoles oblong, 7-8 × ca. 1 mm, gland-tipped pubescent, apex obtuse. Flowers basally to 1 cm apart on rachis but apically becoming congested. Calyx 0.8-1.2 cm, accrescent in fruit, gland-tipped pubescent, 5-lobed almost to base; lobes linear-oblong, 7-10 × ca. 1 mm, subequal, apex obtuse. Corolla purplish blue, 3.5-4 cm, outside pilose, inside glabrous except for trichomes retaining style; tube basally cylindric and ca. 2 mm wide for ca. 1 cm then abruptly inflated, bent to ca. 90° above middle, and finally widened to ca. 1.4 cm at mouth; lobes ovate, ca. 5 × 5 mm, apex rounded. Stamens 4, included; filaments glabrous, shorter pair ca. 2 mm, longer pair ca. 4 mm; anther thecae oblong, ca. 2 × 1 mm, erect; pollen type 4. Ovary comose; style ca. 3.2 cm, sparsely pilose. Capsule oblong, 1.5-1.8 cm, apically gland-tipped pubescent, 4-seeded. Fl. Aug-Sep, fr. Oct-Dec.

● Forests; 1400-3600 m. Chongqing, Guizhou, Hubei, Sichuan, Yunnan.

Strobilanthes flexa appears to intergrade with S. versicolor and may just be a more robust form.