Description from Flora of China
Perennials or rarely annuals, usually glabrous, rarely sparsely glandular hairy on inflorescence axes, pedicels, calyces, and capsules. Rhizomes inclined. Stems erect or procumbent at base, branched or not, 10-100 cm tall, succulent. Leaves sessile, amplexicaul upward; leaf blade elliptic to ovate, sometime ovate-oblong, rarely lanceolate, 2-10 X 1-3.5 cm, margin entire or sparsely serrate. Racemes axillary, many flowered, longer than leaves, often less than 1 cm wide. Pedicel 4-10 mm in fruit, as long as or longer than bract, ascending, at acute angle with inflorescence axis, curved upward in fruit and thus capsule close to inflorescence axis. Calyx 4-lobed; lobes ovate-lanceolate, ca. 3 mm, equal in size, erect or patent, not appressed to capsule in fruit, apex acute. Corolla pale blue, pale purple, or white, rotate, 4-5 mm in diam.; tube short; lobes broadly ovate, slightly unequal in width. Stamens shorter than corolla. Capsule subglobose, as long as wide, slightly compressed, as long as calyx, apex rounded and slightly notched. Style 1.5-2 mm. Seeds numerous, slightly flattened, convex on both sides. Fl. Apr-Sep. 2n = 36.
By water or in swamps; below 4000 m. Anhui, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Jilin, Liaoning, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan [Kazakhstan, Korea, Kyrgyzstan, Mongolia, Nepal, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; Europe, naturalized in North America].