Description from Flora of China
Annuals, glabrous. Rhizomes slender, long. Stems 8-25 cm tall, erect or ascending. Leaves narrowly elliptic to lanceolate, 7-23 X 2-7 mm, base semiamplexicaul, margin entire, apex apiculate; veins 3, inconspicuous. Flowers sessile or subsessile. Bracteoles linear-lanceolate, 4-4.5 mm, herbaceous. Calyx 3-4 mm; lobes linear-lanceolate to oblong-lanceolate, margin membranous. Corolla white or yellowish, 5-7 mm, 2-lipped; tube cylindric, 4-4.5 mm; limb shorter than tube; lower lip lobes obovate, sometimes concave; upper lip apex obtuse to concave. Filaments ca. 0.6 mm; staminodes 2, short, clavate, inserted at base of lower lip. Stigma 2-lobed. Capsule dark brown, globose, 4-5 mm in diam. Seeds slender, long. Fl. and fr. May-Jul.
Fields, beside water; low elevations. Heilongjiang, Jiangsu, Jiangxi, Jilin, Liaoning, Yunnan [Japan, Korea, E Russia].