The Xylarium of Tervuren (Tw) : the collection of wood includes 56,000 specimens of 13,600 different botanical species from around the world. It is therefore the second largest collection in the world and the largest in Europe. It contains wood from all growing plant forms which produce secondary xylem. Lignified plant tissues are omnipresent in the terrestrial living nature. Also a big part of the material culture consists of wooden objects. Because of the multifunctional character of wood, the Tervuren Xylarium should in principle serve the different disciplines interested in wood research: technology, ecology, palaeontology, art history, archaeology, etc. Since the Tervuren Xylarium is the only governmental wood collection in Belgium there is no geographical limitation: it has a worldwide concern. Because of the scientific nature of the collection, the validation of it depends largely on derivative collections like thin sections for microscopy and microphotographs. Moreover there are collections of stem discs that make dendrochronological research possible.