Small herb, prostrate, pubescent, up to 50 cm high; stem much branched, terete at internodes; leaves ovate-elliptic, linear-lanceolate, 2-8 x 0.5-3 cm, acute at apex, narrowed at base, entire or undulate, sparsely hairy or glabrous; flowers axillary, usually solitary or few together; bracteoles large, foliaceous, elliptic-ovate, shortly stalked; calyx divided to more than half of its length, teeth-5, linear, subulate, acute, ciliate; corolla pale pink-violet or sometimes white, subequally 5-lobed, caducous, pubescent outside, twice as long as the length of the tube; stamens 4 included, filaments glabrous; capsule clavate, 2.5 cm long, brown, pubescent; seeds orbicular with hygroscopic hairs.