Erect, perennial, rhizomatous herbs. Leaves opposite, petiolate, denticuate to serrate or occasionally subentire. Inflorescence a raceme or a branched panicle of racemes, terminal on the main stem and at the tips of the uppermost xillary branches. Flowers 2-merous, the stamens opposite the sepals. Petals notched at the apex, rarely emarginate. Stigma bilobed. Fruit uni- or bilocular with single seed in each locule; an indehiscent capsule covered with stiff, uncinate airs. Floral tube deciduous after anthesis.