Description from Flora of China
Fordiophyton longipetiolatum S. Y. Hu; F. polystegium Handel-Mazzetti.
Herbs or sometimes shrublets, 0.6-2 m tall, much-branched. Stems 4-sided, sulcate, glabrous, usually pilose or setose at nodes. Petiole 8(-25) mm or less, sometimes white small maculate, glabrous; leaves of a pair highly unequal and asymmetric, leaf blade broadly lanceolate, 6.5-11.5(-15) × 2-4(-5) cm, oblique, membranous, both surfaces sparsely puberulous, abaxially sometimes white small maculate, secondary veins (1 or)2 on each side of midvein, base shallowly cordate to oblique, margin serrulate with each tooth having a terminal seta, apex acuminate. Inflorescences terminal cymes, ca. 8.5 cm, with glandular trichomes; bracts cordate, ca. 4 mm, membranous, caducous, glabrous. Pedicel short. Hypanthium ca. 4 mm, 8-ribbed, with white small macula, with sparse glandular trichomes or glabrescent. Calyx lobes triangularly broadly ovate, with sparse glandular trichomes or not, base auriculate, margin entire, apex with 1 glandular trichome at tip. Petals reddish or purple, oblong, ca. 1 cm, appressed sparsely strigose, apex oblique with 1 glandular trichome at tip. Longer stamens purplish red; filaments ca. 1 cm, glabrous; anthers linear, ca. 1.5 cm, curved, base lengthened and forming a forked spur ca. 3.5 cm. Shorter stamens yellow; filament ca. 7 mm; anthers oblong, ca. 4 mm, base spurred. Ovary inferior, 4-celled, apex with a membranous ciliate crown. Capsule campanulate, 6(-5) mm in diam., 4-lobed, membranous crown exserting calyx by ca. 2 mm; hypanthium glabrous or with sparse glandular trichomes. Fl. (Aug-)Sep, fr. Dec.
Dense forests, hillsides, valleys, damp and shaded places, grassy areas; 900-2200 m. Guangxi, Yunnan [Vietnam].