5-Hy-droxy-8,8-dimethyl-10-(2-methyl-but-3-en-2-yl)-2H,6H-7,8-dihydro-pyrano[3,2-g]chromene-2,6-dione.

In the title compound, C(19)H(20)O(5), the pyran ring is in an envelope conformation, whereas the benzene and dihydro-pyran ring system is planar with an r.m.s. deviation of 0.0190 (1) Å. The hy-droxy group is coplanar with the attached benzene ring [r.m.s. deviation = 0.0106 (1) Å]. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol-ecules are linked into chains along the b axis by weak C-H⋯O inter-actions. These chains are stacked along the a axis. C-H⋯π and weak π-π inter-actions [centroid-centroid distance = 3.7698 (7) Å] are also observed.