Mariosousa willardiana, also called Palo Blanco tree, palo liso, guinola and Willard Acacia, is a normally evergreen plant in the genus Mariosousa native to Mexico. The Spanish common name translates into 'white stick', defining its peeling white bark. A compound called Willardiine, that acts as an agonist in glutamate receptors, can be isolated from M. willardiana.