BRACKEN or BRAKE a genus of ferns (Pteris or Pterid ium). The common bracken (Pteris aquilina or Pteridium aquilin um) is abundant in most parts of the world. It has a perennial, black rhizome, which creeps extensively underground and at in tervals sends up fronds. These fronds may reach a height of 4f t. or more, and, although dying in autumn, often remain standing throughout the winter, affording in some regions cover for game. The fronds are used for thatching and for littering cattle and occasionally as fodder. (See FERN.) In North America there are three forms of the bracken: the western bracken (Pteridium aquilinum var. pubescens), with more or less hairy fronds, found from Alaska to Montana and southward to Mexico ; the bracken of eastern North America, which, though closely resembling the Old World form, is generally regarded by American botanists as a distinct species (P. latiusculum) ; and the southern form (P. cnudatum), which occurs in southern Florida and Texas.