BOLETUS, in botany, a genus of the cryptogamia fungi class. This mushroom is horizontal, spongy, and porous below. There are 14 species, of which seven are natives of Britain, viz. the suberosus, or cork boletus; the fomentarius, or spongy boletus; the versicolor, or striped boletus; the albus, or white boletus; the ignarius, or hard boletus, or touchwood; the bovinus, or brown boletus; and the luteus, or yellow boletus.