Herbaria in the Netherlands. Their lasting importance for the preservation of biodiversity Most Dutch academic herbarium collections are nowadays deposited in the National Herbarium of The Netherlands (NHN). In this article the various accessions in this collection are described and changes in their use for research over time are highlighted. Three reasons are given for the necessity to continue accepting new accessions at NHN. First of all, global biodiversity changes continuously and these changes need to be monitored and described. Secondly, herbaria are consulted more and more often to find answers to socially relevant questions. Thirdly, the development of ancient DNA techniques makes it possible to extract and analyse DNA present in old herbarium accessions. This created new perspectives for exciting and innovative research at universities all over the world.