El Yunque flora
Among El Yunque’s flora are over 1,000 plant species. There are over 240 species of native trees, of which 88 are rare and 23 are found only in this forest. While many tree species are indistinguishable to the casual observer, the Sierra Palms (Prestoea montana) are easily identified by their red “buttress” roots. There are 50 species of native orchids and over 150 species of ferns, including giant tree ferns (Cyathea arborea) that grow to heights of over 40 feet. The rainforest is commonly divided into four ecological zones characterized by variations in climate, soil and slope. Each zone is named for the dominant tree species. The Tabonuco Forest grows below 2,000 feet in elevation, the Palo Colorado Forest above 2,000 feet, the Sierra Palm Forest above 1,500 feet and the Dwarf Forest, near the ridge tops, as high as 3,500 feet above sea level.