Philipp Franz von Siebold was a nineteenth century German doctor and botanist, who worked for several years in Japan, accumulating an extensive collection of plants and animals from that area.  He was responsible for the introduction of  a number of (now common) garden plants to Europe - such Hostas and Hydrangea. Siebold is almost unknown outside Japan except among gardeners as many plants incorporate sieboldii and sieboldiana in their specific names - for example, species of Primula, cherry (Prunus), Sedum and Viburnum.  Siebold was also associated with the introduction of tea cultivation to Java.  On his return to Europe, he was based in Leiden where he worked on cataloguing and identifying his twelve thousand botanical specimens.   Unfortunately, one of the plants that Siebold introduced was the Japanese knotweed (Reynoutria japonica, syn. Fallopia japonica). This has become a highly invasive weed in Europe and North America. The plant was discovered growing on the side of a volcano; it was named as the “most interesting new ornamental plant of the year” by the Society of Agriculture and Horticulture in Utrecht. Read more...