Rhizomatose herbs, rooting at the nodes. Leaves radical and scattered, margin apically serrulate. Inflorescence a dense or lax thyrse, composed of many2-25-flowered cincinni, indument including outer side of tepals composed of hairs with or without slightly swollen top-cells. Flowers zygomorphic; tepals slightly unequal in size, the 3 abaxial ones basally connate as are the 3 adaxial ones, creating a more or less bilabiate appearance; stamens 3, the 2 adaxial ones smaller than the abaxial one, stamens of the outer whorl replaced by 2 staminodes, outer adaxial staminode lacking; ovary superior, globose in outline to 3-lobate in cross-sectionwith 3-6 ovules per locule on a peltate placenta, stigma undivided, papillate. Capsule with 2-4 seeds per locule; seeds subglobose, tuberculate.