Palm surveys in most representative wetland forest ecosystems were carried out in the lower Ucayali and upper Huallaga River valleys, in the lowland and Andean piedmont regions of Peruvian Amazonia, respectively. These ecosystems are characterized by the species association, density, and vertical distribution of their palm communities. Palms may form almost monospecific stands, e.g., Mauritia flexuosa swamps (aguajal), or multispecific communities, e.g., the seasonal swamp forests in upland valleys (bosque de quebrada) which are dominated by Euterpe precatoria, Jessenia bataua, Mauritia flexuosa, and Socratea exorrhiza, and the forests on periodically flooded alluvial soils (restinga) dominated by some species of the genera Astrocaryum, Phytelephas, and Scheelea. Palm diversity is very low in the forests which are periodically flooded by blackwater streams (tahuampa); palm density, however, is often high with a characteristic patchy distribution due to clustered species. © 1990.