Diversity and abundance relationships of vascular epiphytes were examined at several sites in southern Florida and Peru with reference to the patchiness of the epiphytic biotope. Mortality rates were measured for four epiphytic bromeliads in southern Florida. The number of main vertical stems produced by a tree was positively correlated with the number of epiphytic individuals supported. Stem diameter had no effect on epiphyte abundance or diversity. The average annual mortality rate approaches 30 percent for Catopsis and Guzmania in southern Florida. Several processes may account for the diversity of epiphytes including habitat diversity, niche differentiation, ecological equivalency, and mass effect (sensu Schmida & Wilson, 1985). Ecological equivalents are most likely maintained by high mortality rates. This, coupled with the inherently patchy biotope, results in highly discontinuous populations especially when populations are small as with many epiphytic orchids. Evolutionary implications of this are discussed.