Erect or diffuse, occasionally armed herbs. Leaves opposite,
sessile or subsessile, entire or irregularly wavy. Flowers sessile, in axillary
cymose fascicles or terminal dense heads or spikes, bluish-purple or white.
Bracts leafy, elliptic or linear-lanceolate, bracteoles linear-subulate. Calyx
tubular, 4-5 lobed. Corolla distinctly or indistinctly 2-lipped, 5-lobed.
Stamens 4, didynamous, filaments glabrous, anthers dithecous. Ovary 2-locular,
ovules few to many in each locule, style filiform, hairy, stigma simple.
Capsules oblong-cylindric, not stipitate. Seeds compressed, with hygroscopic
white hairs, oblique-ovate or orbicular, retinacula hook-like.