Annual herb, procumbent or diffused; stem swollen at the nodes, somewhat 4-angled, covered with stout, white prickly bristles; leaves opposite, lanceolate or elliptic, crenate, obtuse at apex, harshly scabrous; shortly petiolate; flowers in axillary or terminal, many-flowered spikes or heads, densely covered with white or very often yellowish brown hairs; bracts large, spathulate or oblong, densely pubescent; bracteoles absent; sepals-5, linear, green, subequal, tube slender; corolla blue or violet, lobes subequal, tube very slender; stamens-4, didynamous, included, anthers oblong, 2-celled, muticous; ovary glabrous, 4-celled, many ovuled, style long; stigma with 1-linear, other very short lobe; capsules 6-8-seeded, glabrous; seeds compressed or ellipsoid, yellowish brown, apperently glabrous when dry, densely hairy with long, white; unicellular hairs.