From Interesting Thing of the Day, a report on the black tulip:

In his 1850 novel The Black Tulip, French author Alexandre Dumas (père) describes a competition, initiated by the Dutch city of Haarlem in the 1670s, in which 100,000 florins (150 florins being the average yearly income at the time) would be given to the first person who could grow a black tulip. Although Dumas’s story is fictional, it is based on a very real phenomenon that took place in the Netherlands in the early 17th century.