Harry Potter descends upon New York

Plants with human bodies that throw parties called mandrakes. All-powerful wands modeled after sinewy snakes. A ferocious dog with three heads aptly named “Fluffy.”

Hanging around inside J.K. Rowling’s head could be fun, mystifying and maybe even downright dangerous.

Rowling’s sketches — of her Harry Potter characters, fantastical creatures and spells — are on display at the New York Historical Society‘s new exhibit, “Harry Potter: A History of Magic.”

Now open through January 27, the exhibition is part of the 20th anniversary of the first US publication of “Harry Potter and the Sorcerer’s Stone.”

The New York show includes items from Rowling’s collection, magical items and folklore that inspired her work and other magical objects and literature from around the world.

“We are expecting an avalanche of people because I think the Harry Potter phenomenon is amazing,” said Roberta J.M. Olson, a New York Historical Society curator. “It’s world-wide, and every child I know is coming.”

The exhibition comes from the British Library, where it ended as its most successful exhibit ever with over 170,000 visitors. (A bonus: There are additional magical items lent by museums on this side of the pond.)

In J.K. Rowling’s own words

As Rowling wrote her famous books, she researched magical folklore, wrote furiously through chapter drafts and sketched it all along the way.

See her sketches of the astonished faces of freckly Ron, Hermione and friends on first encountering Fluffy and check out the chart she drew to help her figure out how the sorting hat worked.

Admire Ron, Harry and Hermione’s costumes from the stage play and artwork from illustrators Brian Selznick, and Kazu Kibuishi. And why not try your hand at mixing a memory potion in a giant cauldron that digitally bubbles and lights up?

Inspiration for Harry Potter’s world

A treasury’s worth of manuscripts, drawings and artifacts dating back to 1600 BC sit beside Rowling’s work, telling the broader history of magic all around the world. (Those mandrakes featured in her books have been wreaking havoc for thousands of years.)

“She didn’t actually take things literally,” said Olson, focusing on Rowling’s research into folkloric objects and books. “She was inspired by them to invent her own. It’s creative. It’s based on something, and that’s why there are all these levels.”

The philosopher’s stone

Harry’s very first adventure, “Harry Potter and the Sorcerer’s Stone,” originally published as “Harry Potter and the Philosopher’s Stone” in the United Kingdom, has him teaming up with his pals Ron Weasley and Hermione Granger to foil an attempt to steal the philosopher’s stone.

The recipe to make that stone is real and is laid out within the 20-foot “Ripley Scroll” dating from around 1570 AD.

The evil Lord Voldemort from the series wasn’t alone in desperately wanting the recipe. For thousands of years people believed the potion could confer everlasting life, and an alchemist named George Ripley put together a list of readily-available ingredients such as enriched sulfur, a chemical bath of mercury and a crescent moon.

The recipe is in the “Potions and Alchemy” room, and curators point out that while alchemy recipes may sound outlandish, they’re actually a precursor to chemistry.

It’s also one of the subjects at Hogwart’s School of Witchcraft and Wizardry, and each room in the exhibit follows along with the curriculum.

The same room holds a book with the oldest known illustration of a witch and the tombstone of Nicolas Flamel. The tombstone and the person are real. Flamel died in Paris in 1418, but in Rowling’s book he’s the curiously old friend of Headmaster Albus Dumbledore.

Find a few tips on pulling mandrakes, those plants with leafy tops and human bodies and behaviors in the “Herbology” room.

In “Harry Potter and the Chamber of Secrets,” the second book in the series, mandrakes make a handy cure when students are turned to stone. In the real world, the plant was believed to be a useful anesthesia.

Professor Pomona Sprout has her Hogwart’s students avoid the mandrakes’ madness-inducing shriek by blocking their ears.

In the 15th century, Giovanni Cadamosto suggested something different in his works of “illustrated herbal” anthologies (plant directories with descriptions of their powers).

From herbs to the heavens

Flaxweed, Toadflax, Fleawort.

Rowling had to come up with a plethora of names for her potions, spells and creatures.

She found some of that inspiration from her copies of “Culpepper’s Herbal,” Nicholas Culpepper’s 17th century list of herbs, a copy of which is on display at the exhibition.

In the astronomy section you’ll find a book called “Astronomical Miscellany” containing the origins of the names “Bellatrix,” “Lestrange” and “Sirius.” The names are all constellations, and Sirius is indeed a collection of stars shaped like a ferocious dog.

Find one of Leonardo da Vinci’s notebooks, an 18th century orrery or model of the universe and a 13th century astrolabe, an astronomy instrument on loan from the American Museum of Natural History.

There’s also the oldest known atlas, which comes from China (circa) 700 AD. “The Dunhuang Star Atlas” charts 1,300 stars. For Chinese astronomers, the stars could foretell what might befall their country’s leader.

Abracadabra and other charms

The exhibit goes far beyond the magic of Harry Potter and into the folklore of the mystical all around the world.

Learn how the word “abracadabra” predates Rowling, Queen Victoria and even the Middle Ages in the “Charms” room.

Roman Emperor Caracalla’s physician explains its use in the 13th century “Liber Medicinalis” or “Book of Medicine.” Try writing the word over and over, and leave out one letter each time. The chant, writes the physician, helps ward off fever and treat malaria.

Next to it find a page from an 18th Century Ethiopian book with a charm for turning yourself into a lion, or, better yet, a python.

Celebrate the anniversary

Curators designed the exhibit to appeal to both children and adults, and although there are plenty of objects that go beyond Harry Potter, cracking a couple of Harry Potter books will add to the appeal.

Act fast to get timed-entry tickets to the New York Historical Society’s exhibition on now through January 27, 2019. Admission includes talks, writing classes and trivia nights.

The exhibit has no plans to travel beyond New York City, but there are several other ways to celebrate Harry Potter’s 20th anniversary. Bet on the adorable Eddie Redmayne or the treacherous Johnny Depp, who plays the villain this time in the second installment of “Fantastic Beasts: The Crimes of Grindelwald” out on November 16.