Plants perennial herbs, with long-creeping, branched rhizomes. Leaves alternate, short- to long-petiolate, the petioles sheathing the stem. Leaf blades simple or trifoliate, glabrous. Stipules absent. Inflorescences racemes, umbels, or appearing as loose clusters. Flowers actinomorphic, perfect, slightly perigynous, often dimorphic (some flowers with exserted stamens and short styles, others with exserted styles and included stamens with short filaments). Calyces deeply 5-lobed, fused to the basal portion of the ovary. Corollas deeply 5-lobed, fused to the basal portion of the ovary. Stamens 5, attached to corolla tube, alternating with the lobes, the anthers attached at or near their bases, dehiscing longitudinally. Staminode-like structures sometimes present. Pistil 1 per flower, of 2 fused carpels. Ovary superior, with 1 locule, the placentation parietal. Style 1, sometimes very short, the stigma 2-lobed, persistent at fruiting. Ovules numerous. Fruits capsules, more or less 2-valved, dehiscing more or less irregularly. Seeds numerous. Five genera, about 45 species, nearly worldwide.

Many earlier authors, including Steyermark (1963), treated these genera as a tribe or subfamily of the Gentianaceae, but more recent morphological, biochemical, and molecular studies (M. H. G. Gustafsson and Bremer, 1995; M. H. G. Gustafsson et al., 1996) have indicated that the two groups are not very closely related. Surprisingly, the Menyanthaceae apparently instead are distant relatives of the lineage leading to the Asteraceae and the non-Missouri families in that group.