Plants 0.5-1.5 m tall, fragrant when dry. Stems often with lower part prostrate and rooting at nodes; young branches quadrangular, sulcate, pubescent or subglabrous; old branches terete, glabrous. Petiole 2-4 cm or slightly longer, puberulent; leaf blade elliptic or ovate, often inequilateral, 3-10(-15) × 2-5(-8) cm, drying thinly papery or membranous, lateral veins 4-7 pairs, slender, both surfaces sparsely pilose, base shortly decurrent, margin distinctly serrate, apex often caudate. Cymes corymbose, 2-4 cm, pubescent; peduncles and branches slender; bracts linear, 2-2.5 mm, apex obtuse. Pedicel 1-2.5 mm. Calyx lobes linear, 1-2 mm. Corolla white except yellow speckled in throat, shorter than 1 cm, outside pilose, inside villous. Capsule broadly pyramidal, 3.5-4.5 mm in diam., wider than long, base truncate, apex contracted, stellate-dehiscent into 4 valves; valves with linear persistent calyx lobes. Seeds reticular striate. Fl. Jun-Sep, fr. Oct-Dec.