Director of the Nationaal Herbarium Nederland (1990-2005)
Professor of Botany, the University of Leiden
for his contributions to the curation of the collections of Philipp Franz von Siebold and Siebold's successors, and for his enthusiastic encouragement of a wide variety of botanical and historical studies
Professor Baas is the first director of the National Herbarium of the Netherlands (Nationaal Herbarium Nederland), the decentralized merger of the herbaria of the universities of Leiden, Utrecht and Wageningen, internationally known by their Index Herbariorum acronyms as L, U and WAG.