In Harry’s second year, in Herbology class, Hogwarts students learn how to safely re-pot mandrakes: leafy humanoid plants that grow from babies to adults. They shriek when removed from the earth, and during infancy, their screams will knock a person unconscious; when fully grown, they are fatal.
The mandrake root is an actual plant from the nightshade family that has a long history of use. In Harry Potter, a brew made from mandrake can cure anyone under a petrification curse, but in the Bible’s Book of Genesis, the root was used to aid conception, and in ancient Greece, it was used as both an anesthetic and an aphrodisiac.
So where did the anthropomorphic qualities—and the screaming—come from? Mandrake roots can resemble humans, particularly babies, which was one of the reasons it became a popular fertility charm to place under one’s pillow in the Middle Ages. In some texts, they were even categorized as “male” and “female,” depending on their shape. And at some point, it was recorded that they shrieked upon being unearthed, causing madness. A 15th-century illustration from Europe instructed the best way to safely pick them: Use a rope to tie the plant to a dog, then blast a horn. The sound will both overpower the mandrake’s howls and frighten the dog so it pulls up the root.
Though it’s unclear why mandrakes were believed to be capable of insanity-inducing screams, perhaps the answer lies in the hallucinogenic properties of the root: It may have caused a number of accidental psychedelic trips over the centuries.
It’s also notable that Rowling was faithful to a particular book when dreaming up Herbology lessons. She referenced Culpeper’s Complete Herbal, published in 1653 by English botanist and apothecary Nicholas Culpeper, which outlines the use of over 400 herbs, and is still in print today. Culpeper, like many knowledgeable herbalists, was tried for witchcraft, though he was ultimately acquitted.