Description from Flora of China
Oldenlandia cryptantha (Dunn) Chun.
Herbs, perennial, procumbent, to 50 cm tall; stems 4-angled, sulcate, glabrous to puberulent, sometimes with wings to 4 mm wide. Leaves sessile to petiolate, sometimes clustered near top of stem; petiole to 15 mm; blade with midrib often purple, drying papery, elliptic, oblanceolate, or obovate, 15-30 × 5-10 cm, glabrous (but sometimes when dry appearing puberulent due to collapsed large epidermal cells), base acute to attenuate and long decurrent, apex acute to long acuminate; secondary veins 5-7 pairs, sometimes with well-developed intersecondary veins; stipules interpetiolar, narrowly triangular, 8-30 mm, glabrous, laciniate or with 5 to numerous setiform segments or lobes 1-20 mm, these sometimes apparently glandular at apex. Inflorescences axillary at nodes well below stem apex, capitate, subcapitate, or congested-cymose, 1.5-2.5 cm in diam., several to many flowered, glabrous, sessile; bracts linear-lanceolate, 5-8 mm, acute to erose or shortly laciniate. Flowers sessile or subsessile, biology unknown. Calyx glabrous; hypanthium portion subglobose, ca. 2 mm; limb lobed essentially to base; lobes linear-lanceolate, 6-8 mm. Corolla white to pale purple, salverform or tubular, outside apparently glabrous; tube 14-16 mm, inside tomentulose from above middle to throat; lobes narrowly ovate, ca. 3 mm. Anthers included, 1-1.2 mm. Fruit indehiscent, obovoid, laterally somewhat flattened, ca. 3 × 2 mm, glabrous, with calyx lobes to 10 mm; seeds angled, black, foveolate. Fl. Sep-Nov, fr. Oct-Jan.
● Forests in humid shady valleys, rock crevices at streamsides; 300-1000 m. Hainan (Lingshui).