Plant collections from various nineteenth-century government expeditions deposited with the National Institute for the Promotion of Science were turned over to the Smithsonian Institution on its foundation in 1846. These, in particular the large collection from the U.S. South Pacific Exploring Expedition, formed the basis for a national herbarium. From this beginning the U.S. collections have grown to over 4 million specimens.
One of the most remarkable of these is the Vascular Plant Type Collection consisting of nearly 70,000 specimens.