Description from Flora of China
Subshrubs or herbs, erect, to 1.5 m tall; stems glabrous, flattened to 4-angled or terete. Leaves sessile to subsessile; blade drying papery, narrowly elliptic-oblong or narrowly elliptic, on vegetative stems, 10-17 × 1.5-2.6 cm, glabrous, base cuneate to acute then usually long decurrent, apex acute to acuminate; secondary veins 6-8 pairs, abaxially indistinct; stipules shortly united around stem or sometimes fused to petiole bases, triangular to narrowly triangular, 8-13 mm, glabrous, long acuminate, marginally sometimes sparsely glandular-serrulate or ‑setose. Inflorescence axillary, paniculate-cymose with small cymes distributed along axes with leaflike bracts and bracteal stipules, or along axillary branches with reduced leaves (depending on interpretation), 7-24 cm, many flowered, glabrous, pedunculate; peduncle 0.5-4 cm; leaflike bracts or reduced leaves paired, lanceolate to narrowly elliptic, 10-40 mm; cymes 8-15 mm, several flowered; floral bracts linear or linear-lanceolate, 2-8 mm; pedicels to 1 mm. Flowers subsessile to pedicellate. Calyx glabrous; hypanthium portion ellipsoid, 1-1.2 mm; limb lobed nearly to base; lobes narrowly triangular, 2-3 mm. Corolla white, tubular, outside glabrous; tube 4.5-5 mm, bearded in throat; lobes spatulate-oblong to triangular, 2-2.5 mm, acute. Anthers exserted, ca. 1.2 mm. Stigma included, ca. 0.8 mm. Fruit capsular, obovoid or subglobose, 2-3 × 2-2.5 mm, glabrous, septicidally then loculicidally dehiscent, cartilaginous; seeds 2-4, brownish black, tuberculate. Fl. almost year-round, fr. May, Jun, Oct.
The inflorescences are borne laterally along well-developed axes with numerous leaflike bracts or reduced leaves, or alternatively along lateral branches with reduced leaves; various morphological descriptions of these have been used by different authors.
● On soil rich in humus in valleys or at streamsides; 900-1000 m. Hainan.