Herbs, perennial, sometimes slightly woody at base; rootstock slender, with short rhizomatous and somewhat woody branches and with ascending or erect stems. Raphides present. Leaves opposite, decussate, subsessile, without domatia; stipules persistent, interpetiolar, hardly fused to petioles, triangular to linear or ± irregularly divided and often mutifid to fimbriate. Inflorescences thyrsoid, with terminal and axillary branches at uppermost nodes, pedunculate cymes often with umbelliform flower groups, not rarely with new axes developing and older axes elongating making inflorescences expansive, lax, few to many flowered and bracteate; uppermost bracts often reduced to multifid or fimbriate stipules. Flowers pedicellate, bisexual, monomorphic. Calyx teeth 4 or 5, narrowly lanceolate, hardly fused at base. Corolla white to pink or red, funnelform, divided to ca. 1/2 into 4 or 5 lobes, glabrous inside and valvate in bud. Stamens 4 or 5, inserted in corolla throat, finally slightly exserted; filaments flattened; anthers dorsifixed near base. Ovary inferior, densely covered with hooked trichomes, 2-celled, ovules 1 in each cell, erect, basal; style with 2 short, linear stigmas, exserted. Fruit with calyx teeth ± persistent, schizocarpous, dividing into 2 oblong to ellipsoid, leathery and indehiscent mericarps, densely covered with hooked trichomes; each mericarp with 1 medium-sized, ellipsoid and plano-convex seed; endosperm fleshy; embryo large; cotyledons leaflike; radicle hypogeous.
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