The molecular and crystalline structures of a tropolone alkaloid of the colchicine series - speciosine - have been determined by x-ray structural analysis. It has been established that the presence of an orthohydroxyphenyl group does not lead to appreciable changes of the colchicine skeleton in the speciosine molecule. In the crystals, the speciosine molecules are linked into zigzag chains through O6-H⋯O1 intermolecular H-bonds.