Description from Flora of China
Herbs perennial, 25--40 cm tall. Stems often many, erect, terete, branched above middle, densely puberulous. Leaves opposite, sessile, lanceolate to narrowly lanceolate, 10--60 X 4--13 mm, tapering toward auriculate semi-clasping base, abaxially with densely pubescent veins and scattered transparent glands, adaxially glabrous; veins 4 or 5 pairs; veinlets invisible. Lowest pedicels to 8 mm, gradually reduced upward, pubescent. Flowers solitary, axillary, often with flowers aggregated near apex of branches in a corymblike cluster. Calyx lobes lanceolate, 4--5 X ca. 2 mm, apex acuminate-subulate; midvein distinctly raised abaxially. Corolla yellow, 6--7 mm, deeply parted; tube 1--2 mm; lobes elliptic, sparsely transparent glandular. Filaments connate basally into a ring, free parts 2--4 mm; anthers dorsifixed, opening by lateral slits. Ovary glabrous; style ca. 5 mm. Capsule brown, subglobose, ca. 2.5 mm in diam. Fl. Jun.
* Grassy mountain slopes. W Hubei, E Sichuan.