I agree it looks like x nobilis, but that is the real parentage of the hybrid. You can distinguish it from nobilis (as pictured above) based on the spines present on the upper side of the leaf, the greater number of spines underneath, the upper surface of the leaf being flat and not slightly concave, probably other differences. With advanced age my plant should also grow a stem (it has already started; the dead lower leaves fall easily away from the stem). Both parents make pretty "pumped up" leaves. The erinacea parent is extra spiny.
