The term cienega is here applied to mid-elevation (1,000-2,000 m) wetlands characterized by permanently saturated, highly organic, reducing soils. A depauperate flora dominated by low sedges highly adapted to such soils characterizes these habitats. Progression to cienegais dependent on a complex association of factors most likely found in headwater areas. Once achieved, the community appears stable and persistent since paleoecological data indicate long periods of cienegaconditions, with infrequent cycles of incision. We hypothesize the cienega to be an aquatic climax community. Cienegas and other marshland habitats have decreased greatly in Arizona in the past century. Cultural impacts have been diverse and not well documented. While factors such as grazing and streambed modifications contributed to their destruction, the role of climate must also be considered. Cienega conditions could be restored at historic sites by provision of constant water supply and amelioration of catastrophic flooding events.