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"This is the most complicated potion I've ever seen. Lacewing flies, leeches, fluxweed, and knotgrass. Well, they're easy enough."
Hermione Granger on the Polyjuice Potion ingredients[src]

Knotgrass is a plant with magical proprieties. It is used in potion-making, and is an essential ingredient in the making of the Polyjuice Potion and in the brewing of alcoholic beverages such as Knotgrass Mead.

Knotgrass can be found growing in the Forbidden Forest. Harry Potter and Hermione Granger struggled through a patch of it on their way back from their first meeting with Grawp, just before they and Hagrid were approached by the centaurs.

Behind the scenes

  • Knotgrass may refer to several species of the Polygonum genus found in England and Europe. It is most likely Polygonum aviculare, which was believed to halt the growth of animals and was mentioned as such in the works of Shakespeare.[1]
  • The use of knotgrass in the Polyjuice Potion was chosen by J. K. Rowling to represent "being tied to another person".[2]
  • In the GBA version of Chamber of Secrets, this is instead received from a Venomous Tentacula.


Notes and references

  1. Grieve, Margaret, and Maud Grieve. A modern herbal: the medicinal, culinary, cosmetic and economic properties, cultivation and folk-lore of herbs, grasses, fungi, shrubs, & trees with all their modern scientific uses. Courier Dover Publications, 1976. (
  2. Pottermore - The Polyjuice Potion - J.K. Rowling's Thoughts

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