Description from Flora of China
Didymocarpus swinglei Merrill, Philipp. J. Sci. 13: 156. 1918; Chirita pellegriniana B. L. Burtt; Didymocarpus balansae Pellegrin (1926), not C. balansae Drake (1890).
Perennial, stemless. Rhizome internodes inconspicuous. Leaves basal, opposite; petiole 0.8-7.5 cm X 2-11 mm; leaf blade elliptic to ovate, obovate, or orbicular, 6-19 X 4-17 cm, herbaceous, strigose, eglandular, base often oblique, broadly cuneate to rounded or truncate, margin denticulate or dentate to crenate, apex acute to rounded; lateral veins 3-7 on each side of midrib, slightly conspicuous. Cymes (1-)3-8-flowered; peduncle 2.8-19 cm, pubescent; bracts 2, free, linear to linear-lanceolate, 2-6 X 0.8-1 mm, puberulent, margin entire, apex acute. Pedicel 2-4(-8) cm, spreading puberulent. Calyx 5-sect from base; segments equal, lanceolate-linear, 6-10 X 1-1.5 mm, outside densely puberulent, inside apically sparsely puberulent, margin entire, apex acute. Corolla bluish to purple, 2.4-4.2 cm, outside sparsely puberulent, inside glabrous or glandular puberulent on adaxial lip; tube campanulate to funnelform, 1.2-2.2 X 0.7-1.2 cm; adaxial lip 7-11 mm; abaxial lip 1-2.2 cm. Filaments ca. 9 mm, sparsely puberulent; anthers fused by entire adaxial surfaces, 2.5-3 mm, glabrous; staminodes 2, 1.2-2 mm. Pistil 1.5-1.7 cm, puberulent; ovary ca. 9 mm. Stigma spatulate to narrowly ovoid, 1-2 mm, undivided. Capsule erect, 2-3.5 cm. Fl. May-Sep, fr. Jul-Oct.
After publication of the family treatment for the Flora of China,
this was treated as Primulina swinglei (Merrill) Mich. Möller & A. Weber (Taxon 60: 785. 2011).
Forests, cliffs in valleys; 600-900 m. Guangdong (Luofushan, Zengcheng Xian), S Guangxi [N Vietnam].