Pietro Andrea Gregorio Mattioli (Italian: [ˈpjɛːtro anˈdrɛːa ɡreˈɡɔːrjo matˈtjɔːli]; 12 March 1501– c. 1578) was a doctor and naturalist born in Siena. His most important work was a commentary on the medicinal plants of Dioscorides first published in 1544 which was translated into several languages and went into thirteen editions in his lifetime.