Description from Flora of China
Herbs, annual. Stems erect, basally woody, apically much branched. Leaves opposite, sessile or short petiolate; leaf blade pinnately parted or dissected. Racemes terminal; bracts foliaceous, parted to entire. Flowers opposite, sparse. Pedicel short. Bracteoles 2, linear. Calyx tube campanulate, 4-8 X longer than wide, membranous, 10-veined; lobes 5, subequal, sublanceolate. Corolla tube slender, straight, as long as or slightly longer than calyx tube; limb 2-lipped; lower lip as long as upper, 3-lobed; lobes ovate-triangular, subequal, apex acute, with 2 petaloid plaits; upper lip galeate, bowed. Stamens didynamous, slightly exserted. Ovary 2-loculed. Style slightly exserted. Capsule black to black-brown, enclosed by persistent calyx. Seeds numerous, oblong-ovoid; seed coat reticulate; wing thick, fleshy, hyaline.
About four species: Asia; two species in China.