Herbs, perennial [or annual], prostrate [to erect], with cystoliths, often anisophyllous. Leaves opposite, long petiolate; leaf blade margin entire or crenate. Inflorescences terminal [or axillary], secund strobilate spikes; bracts subleaflike, orbicular or reniform, imbricate; bracteoles [present or] absent. Flowers sessile. Calyx 5-lobed almost to base; lobes unequal, posterior one largest. Corolla small; tube cylindric, slender; limb ± 2-lipped, lower lip 3-lobed, upper lip 2-lobed; lobes contorted in bud. Stamens 4, didynamous, included in corolla tube; filaments coherent at base; anthers 2-thecous; thecae parallel, base minutely mucronate [or not mucronate]. Ovary with 2 ovules per locule; style hairy; stigma 2-lobed, lobes unequal. Capsule shortly stipitate, 4-seeded; retinacula present; septa with attached retinacula separating from inner wall of mature capsule. Seeds discoid, densely covered with hygroscopic trichomes.
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