Description from Flora of China
Herbs tall perennials. Leaves petiolate, margin dentate. Verticillasters many flowered, in terminal spikes. Calyx tubular-obconical, straight, 15-veined, not hairy annulate inside, throat oblique. Corolla tube straight, gradually dilated to throat, as long as to slightly longer than calyx, not hairy annulate inside, 2-lipped; upper lip straight, 2-lobed; lower lip spreading, 3-lobed, middle lobe widest, spreading, base not clawed, margin undulate, lateral lobes straight. Stamens 4, fertile, much exserted, posterior 2 longer and inclined forward, anterior 2 erect-ascending; anther cells 2, initially almost parallel, later ± divergent. Style subequally 2-cleft. Nutlets smooth, apex hairy.
Nine species: eight in North America and one in E Asia.