The title sesquiterpene [systematic name: 6-methoxy-10-methyl-7-(propan-2-yl)-2-oxatricyclo[6.3.1.04,12]dodeca-1(11),4,6,8(12),9-pentaen-5-ol], C16H18O3, was isolated from pathogen-infected stele tissue ofGossypium barbadense. There are two molecules in the asymmetric unit and the dihedral angle between their naphthofuran systems is 86.48 (2)°. In the crystal, O—H...O hydrogen bonds between the hydroxy groups and etheric O atoms link the molecules into centrosymmetric tetramers. These tetramers are assembled into (010) layersviastacking interactions between the naphthofuran systems [interplanar distance 3.473 (3) Å] and short C—H...O contacts.