One of the most written about plants in history with whole books devoted to its properties and its ability to scream when pulled from the ground.
By tato grasso (Own work/personal work) [CC BY-SA 2.5], via Wikimedia Commons (http://creativecommons.org/licenses/by-sa/2.5)
"Instead of roots, a small, muddy, and extremely ugly baby popped out of the earth. The leaves were growing right out of his head. He had pale green, mottle skin, and was clearly bawling at the top of his lungs." Harry Potter and the Chamber of Secrets, J. K. Rowling
Harry Potter's World
Because plants and their uses are important to wizards, all students at Hogwarts are required to take Herbology. In Harry's second year, he learns how to grow mandrakes, real plants studied by historical botanists. Although it isn't his favorite subject, the young wizard soon comes to appreciate Herbology when he discovers that mandrake is the key ingredient of a potion that will cure his severely injured classmates. In his fourth year, Harry is once again reminded of the value of studying plants when he must find a way to breathe underwater during the Triwizard Tournament. Harry's classmate teaches him about gillyweed, a fictitious plant that, when ingested, gives its user fins and gills.
The History of Science
Historically, scholars believed that studying plants could provide clues as to how nature works and, in 1491, publisher Jacob Meydenback compiled earlier writings into the Hortus Sanitatis. This single volume catalogued hundreds of plant species and their uses, including those of the poisonous mandrake. At the time, many believed that mandrake roots resembled the human figure and possessed magical powers including the fatal scream fictionalized in Harry Potter. Historical botanists and physicians also recognized the mandrake’s medicinal value and sometimes used small doses of the plant as an anesthetic.