Between 1829 and 1866 the Bavarian physician Philipp F.B. von Siebold (1796—1866) introduced many garden plants from Japan into Europe, some to be the first Japanese plants to reach Europe. Several of these species became naturalized in the Dutch flora. Completely naturalized are Fallopia japonica and Rosa rugosa, and probably also Berberis thunbergii, Cyrtomium falcatum, Ligustrum ovalifolium, Petasites japonica, and Rosa multiflora. Elaeagnus pungens, E. umbellata, Lycium chinense, Pachysandra terminalis, Parthenocissus tricuspidata and Spiraea japonica are also sometimes found naturalized.