Herbs perennial, erect, 20--55 cm tall, aromatic when dry. Stems angular, simple or slightly branched in upper part, glandular at apex. Leaves alternate, evenly distributed on stem; petiole to 1.5 cm; leaf blade lanceolate, 2.5--6.5(--8) X 0.7--1.7 cm, adaxially glabrous or sparsely bristly, base attenuate, margin obscurely undulate, apex acuminate. Pedicel filiform, 2.5--3.5 cm. Flowers solitary, axillary. Calyx lobes ovate, ca. 2.5 mm, copiously minutely glandular inside, apex acuminate. Corolla yellow, deeply parted; lobes narrowly oblong, 4--5 X 1.6--1.8 mm, apex subobtuse. Filaments connate basally into a ca. 0.5 mm high ring, free parts very short; anthers 3--4 mm, basifixed, opening by apical pores. Style filiform, ca. 4 mm, ca. as long as stamens. Capsule globose, ca. 3 mm in diam., longer than calyx. Fl. May.

Mixed forests; 1500--2200 m. S Yunnan [N Thailand].