one of the great tropical botanical gardens and arboretums of the world. It was founded in 1808 by John, prince regent of the United Kingdom of Brazil and Portugal (later King John VI), for introducing and acclimatizing economically beneficial plants brought from other tropical regions of the world. The garden, located on a 350-acre (141-hectare) site below high peaks, has a collection of more than 7,000 species of tropical plants. Native Brazilian plants such as aroids, palms, and woody members of the legume family predominate. A striking feature of the garden is its spectacular avenues of royal palms that measure about 100 feet (30 metres) high. The garden maintains an herbarium that has approximately 330,000 reference specimens, a fine library, and well-equipped research laboratories. It lies along a main avenue linking the districts of Botafogo and Gávea in Rio de Janeiro.