The introduction of the tulip to Europe is often questionably attributed to Ogier de Busbecq, the ambassador of Ferdinand I, Holy Roman Emperor, to the Sultan of Turkey, who sent the first tulip bulbs and seeds to Vienna in 1554 from the Ottoman Empire. Tulip bulbs, along with other new plant life like potatoes, peppers, tomatoes and other vegetables, came to Europe in the 16th century. These bulbs were soon distributed from Vienna to Augsburg, Antwerp and Amsterdam. Their popularity and cultivation in the United Provinces (now the Netherlands) is generally thought to have started in earnest around 1593 after the Southern Netherlandish botanist Carolus Clusius had taken up a post at the University of Leiden and established the "hortus academicus". He planted his collection of tulip bulbs and found that they were able to tolerate the harsher conditions of the Low Countries; shortly thereafter, the tulip began to grow in popularity.