A genus that is confined to the sandstone tepuis of northern South America. It represents an unusual monocot family that is restricted to tropical South America, except for the monotypic Maschalocephalus, which occurs in a sandstone region of Liberia and Sierra Leone in West Africa. Whether this disjunction is due to long distance dispersal or to vicariance (the sandstone area of West Africa representing a chip off the old Gondwanaland block that split from South America in the Cretaceous) is not known.