Description from Flora of China
Mazus crassifolius P. C. Tsoong; M. neriifolius H. L. Li.
Perennials, 10-30 cm tall, stout, glabrous or sparsely villous. Rhizomes short or to 15 cm. Leaves all basal, rosulate; leaf blade obovate-spatulate to spatulate, 3-20 cm, thick papery to subleathery, abaxially glaucous, adaxially green and bright, base tapering, margin sparsely and coarsely toothed, apex rounded to obtuse. Scapes 1(-4), herbaceous, erect or ascending, striate. Racemes lax flowered; bracts narrowly lanceolate, to 6 mm. Pedicel 1-1.5 cm, glandular hairy. Calyx campanulate, ca. 7 mm; lobes ca. 1/2 as long as tube, ovate-triangular, veins inconspicuous. Corolla light blue-purple, 2-3 cm; tube enlarged near throat; lower lip margin erose-toothed, apex truncate and emarginate; upper lip erect, shorter than lower lip, lobes ca. 4 mm wide, apex rounded. Ovary glabrous. Capsule ovoid, ca. 5 mm. Fl. Apr-Jul, fr. Jul-Sep.
The whole plant is used medicinally.
* Moist crevices; 500-2000 m. NW Guizhou, SW Sichuan.