Enterolobium cyclocarpum is its scientific name and it was declared the national tree of Costa Rica in 1959 as a tribute to the people of the Guanacaste province that were annexed to the country in 1824.
The name Guanacaste comes from the Aztec word Guautil which means tree and Nacaztli which means ear, which refers to the fruit of this plant and its resemblance to a human ear.