Bog

bog, type of wetland ecosystem characterized by wet, spongy, poorly drained peat-rich soil. Bogs can be divided into three types: (1) typical bogs of cool regions, dominated by the growth of bog mosses—sphagnums (mosses of the genus Sphagnum)—and heaths, particularly leatherleaf (Chamaedaphne); (2) pocosins, or evergreen shrub bogs, of the southeastern United States; and (3) tropical bogs, or tropical tree bogs, in which the peat may be formed almost entirely from tree remains. Typical, or sphagnum, bogs are highly acidic, with a pH (index of acidity and alkalinity) of less than 5 (7 being neutral), and are associated with waters containing no more minerals than are contained in rainwater, often the only source of water for a bog. Tropical bogs occur only in areas where the water is very low in minerals. They are less common than swamps but still cover extensive areas in Malaya, Indonesia, tropical South America, and Africa.