The Leiden branch of the Nationaal Herbarium Nederland (NHN-Leiden) combines two institutions with a long history. The Leiden Botanic Garden was founded in 1590 as the earliest scientific garden in Western Europe. It immediately became of great botanical significance thanks to its first director, Carolus Clusius, and curator Cornelis Clutius who jointly introduced many exotics, and saw to it that the scientific value of the Hortus far transcended that of a medical garden. The Garden was to play an important role in botanical research and teaching, and was also instrumental in the introduction of many ornamental plants from the Mediterranean and the Far East to the Netherlands. In 1988 it was united with the Rijksherbarium to form the first 'Research Institute' within the Faculty of Mathematics and Natural Sciences of the University of Leiden. Since 1 January 1999, the Rijksherbarium is a part of the Nationaal Herbarium Nederland (National Herbarium of the Netherlands, NHN). This institute consists of the herbaria associated with the universities of Leiden (L), Utrecht (U), and Wageningen (WAG).
The Rijksherbarium was founded in 1829 by Royal Decree of King William I. Its first residence was in Brussels. C.L. Blume, an outstanding botanist and pioneer of Malesian botany, was its first director. In the early days of the separatist uprising in Belgium in 1830 the great explorer of Japan, Philipp Franz von Siebold, and the director's assistant J.B. Fischer transferred the Rijksherbarium collections to Leiden. Here the institute was to develop into what it still is today: an active research centre focusing both on European and Indo-Malesian plant diversity, thereby facilitated by an evergrowing collection of great international importance. With its current collection of over four million plant specimens and a tenured staff of 18 scientists, 20 PhD students, a varying number of graduate students and numerous honorary and contract researchers, the NHN-Leiden one of the foremost institutes of systematic botany in the world, and an important core institute of the National Research School 'Biodiversity'. It is fully committed to the three main tasks outlined in the Systematics Agenda 2000: 1) to discover and 2) to help understand plant biodiversity, and 3) to manage and disseminate biodiversity information.