The Hortus Botanicus was founded in 1590 by students and professors of the University of Leiden. Researchers grew tropical trees and plants in greenhouses. In 1593, the botanist Carolus Clusius brought the first tulip bulbs into Holland and planted them at the Hortus Botanicus. The original gardens have been reconstructed in the Clusius Garden – named after Carolus Clusius in acknowledgement of his scholarly works. The National Herbarium of the Netherlands is a part of the Hortus Botanicus, and is one of the largest Herbaria in the world.