The title compound, erioflorin, C19H24O6 [systematic name: (1aR,3S,4Z,5aR,8aR,9R,10aR)-1a,2,3,5a,7,8,8a,9,10,10a-deca-hydro-3-hy-droxy-4,10a-dimethyl-8-methyl-idene-7-oxooxireno[5,6]cyclo-deca-[1,2-b]furan-9-yl methacrylate], is a tricyclic germacrane sesquiterpene lactone, which was isolated from