Annual herb, erect or prostrate, herbaceous, hairy; braches 4-angled, grooved, more or less pubescent, swollen at the nodes; leaves opposite, variable in shape, ovate-lanceolate or elliptic-oblong, acute at apex, subentire, glabrous or pubescent; flowers in terminal or axillary, dense, much broad, hairy, cylindric spikes; bracts elliptic-ovate, slightly longer or as long as calyx, margins scarious, ciliate or with white, glistening, many jointed hairs; bracteoles similar to bracts but narrower; calyx 4-partite, sepals unequal in length, linear-lanceolate, subacute, margins scarious, densely hairy; corolla small, pale purple or white, hairy outside, tube equalling the limbs, throat mottled inside; stamens 2, scarsely exserted, anthers 2-celled, cells oblong, filament hairy at the base; ovary ovate or ellipsoid, hairy, style filiform, stigma bifid; capsule ovoid or ellipsoid, cylindric, 4-seeded; seeds ovoid, compressed, scaly, glochidiate or spinescent, never with fine, elastic hairs springing out when moistened.