Oncocalamus is a monoecious genus of flowering plant in the palm family found in western Africa. The genus is the lone member of the Oncocalaminae; once placed with the vegetatively similar Eremospatha and Laccosperma in the Ancistrophyllinae, it is now isolated based on their unusual flowers and arrangement. Such a placement argues for a long and complex evolutionary process in the Calamoideae with heavy extinction rates. The Greek genus name combines "horn" and "capsule".