Description from Flora of China
Herbs, hemiparasitic, erect, rigid, black when dry, usually scabrous. Leaves basally opposite, apically alternate; leaf blade margin entire, often coarsely toothed at stem base. Inflorescences spikes or spicate racemes. Bracteoles 2. Calyx tubular, veins 10, sometimes inconspicuous; lobes 5, short. Corolla lobes 5, subequal. Stamens 4, didynamous, included; anthers 1-loculed, erect, dorsifixed, base obtuse, apex mucronate. Style apically clavate; stigma entire or incised. Capsule loculicidal; valves entire. Seeds numerous, somewhat dorsiventrally compressed.
About 60 species: tropical to subtropical regions; one species in China.