An <i>Amanita</i> Mushroom (IMAGE) University of California - Riverside Caption The Amanita mushroom, seen here growing in a forest in Oregon, is a fungus. The white material on the mushroom represents patches or warts that remain when, as part of its development, this type of fungus breaks through the tissue enclosing the entire button mushroom. Credit Stajich lab, UC Riverside. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.