Some of the trees of the El Yunque National Forest’s upper zones have adapted to its unique soil, topography and humid climate conditions by growing “buttress roots,” a type of prop root that grows at the base of the tree trunk, extended and flattened along its upper surface to form a support for the tree. A good example of this adaptation is the Sierra Palm (Prestoea montana); rather than burying its roots, this tree grows exposed “buttress” roots which help it cling to,unstable soils, steep cliff edges and river banks in the forest’s 5,000 acre (2000 hectare) Sierra Palm Life Zone which begins in the El Yunque National Forest above 1400 feet in elevation. Because buttress roots extend along the ground’s surface, they also serve to increase the area over which the tree can absorb nutrients from the soil through osmosis. . . . article written by Alan Mowbray for El Yunque.com Read more about rainforest soils, climate, topography and the Sierra Palms.