Description from Flora of China
Torenia concolor var. formosana T. Yamazaki; T. radicans Vaniot; T. rubens Bentham.
Herbs, creeping. Stems quadrangular, rooting from nodes; branches ascending or erect. Petiole 2-10 mm; leaf blade triangular-ovate, narrowly ovate, or rarely ovate-orbicular, 1-4 X 0.8-2.5 cm, glabrous or sparsely villous, base broadly cuneate to subtruncate, margin serrate or crenate and serrate, apex obtuse to acute. Flowers axillary or terminal, solitary or in fascicles. Pedicel 2-3.5 cm, to 5 cm in fruit. Calyx 1.2-1.7 cm, to 2.3 cm in fruit, base decurrent; wings 5, slightly more than 1 mm wide; lips narrowly triangular with 5 small lobes evident in fruit. Corolla blue to blue-purple, 2.5-3.9 cm, exceeding calyx lobes by 1.1-2.1 cm. Anterior stamens appendages filiform, 2-4 mm. Capsule 1.5-1.8 cm. Fl. and fr. May-Nov.
Forests, mountain valleys, trailsides; below 1500(-2500) m. Guangdong, Guangxi, Guizhou, Hainan, Taiwan, Yunnan [Japan (Ryukyu Islands), Laos, Vietnam].