Short answers, pulled from the story.
Carolus Clusius, born Charles de l'Ecluse on the 19th of February 1526 in Arras, was a sixteenth-century botanist considered one of the most influential scientific horticulturalists of his era. He introduced the tulip, potato, and horse chestnut to European cultivation, helped establish one of the earliest formal botanical gardens at Leiden, and built a correspondence network of roughly 1,500 letters from 320 correspondents across Europe.
Clusius received exotic bulbs at the imperial garden in Vienna, where he served as prefect from 1573, partly through the efforts of Ogier Ghiselin de Busbecq, who had arranged for bulbs to be sent from the Ottoman court at Constantinople. After his appointment as professor and garden prefect at the University of Leiden in October 1593, Clusius cultivated tulips there, laying the foundation for the Dutch tulip bulb industry.
Tulip breaking is a phenomenon in which a tulip plant spontaneously develops vivid flame and feather color patterns. Clusius documented and studied these striking varieties during his time at the Leiden botanical garden. The cause was identified in the late nineteenth century as a virus; Clusius had no knowledge of that mechanism but his careful observations of the phenomenon directly influenced the speculative tulip mania of the 1630s.
Clusius published his first work, a French translation of Rembert Dodoens's herbal, in 1557. His two major original works were a study of Spanish flora in 1576 and a study of Austrian and Hungarian alpine plants in 1583. His collected works appeared as Rariorum plantarum historia in 1601, which included a pioneering study of Central European mushrooms, and Exoticorum libri decem in 1605, a survey of exotic flora and fauna.
Clusius studied at Louvain, Marburg, Wittenberg, and the University of Montpellier, where he trained under professor Guillaume Rondelet from 1551 to 1554. He later worked for the Fugger banking family in Spain, served as prefect of the imperial medical garden in Vienna from 1573, spent time in Frankfurt am Main, and became professor and first praefectus of the Hortus Academicus at the University of Leiden in October 1593.
Clusius was the first botanist to climb the Ostercher and the Schneeberg in Lower Austria. His ascent of the Schneeberg was also the first documented climb of that mountain by any person. These climbs were part of his broader study of Austrian alpine flora, undertaken under the auspices of Emperor Maximilian II.