The genus Suillus was first defined by Pier Antonio Micheli in his 1729 work Nova plantarum genera, however it is not valid as it predates the 1753 start of Linnean taxonomy.[3] Fries sanctioned the use by British botanist Samuel Frederick Gray in the first volume of his 1821 work A Natural Arrangement of British Plants. Setting Suillus luteus as the type species, he described the genus as those mushrooms with a centrally placed stipe, a distinct ring, a circular cap, and tubes that are stuck together