The Herbarium Hamburgense of the University of Hamburg (acronym HBG) is the 4th largest herbarium in Germany and holds a collection of more than 1.8 million preserved plant specimens. All plant groups, e.g. flowering plants, ferns, mosses, lichens, fungi and algae are covered. The scope is worldwide and the collections span a period of 300 years. There are special collections such as the bulky specimens and alcohol collections, galls and teratologia as well as the autograph and portrait collection. The collections are growing by field studies of staff and members of the Biodiversity, Evolution and Ecology working group of the Biocenter Klein Flottbek of the the University of Hamburg. So far, almost 40000 herbarium sheets have been fully digitized including nearly 20000 type specimens.