Cowbane

• Type: Magical Plant, Potion Ingredient
• Primary Use: Ingredient in the Shrinking Solution
• Part Used: Sprig

Cowbane is a magical plant used in Potions. The precise appearance of the magical variety of Cowbane is not described in the novels, but the use of a “sprig” suggests it is a leafy or herbaceous plant. Its real-world counterpart, also known as water hemlock, is a green, flowering plant with fern-like leaves, and it is highly toxic.

The primary known magical property of Cowbane is its function as a key ingredient in the Shrinking Solution, a potion that causes the drinker to shrink in size. In the standard brewing instructions for the Shrinking Solution, one sprig of Cowbane is added at a late stage in the process. It is added after the mixture has simmered for five minutes with ingredients such as rat spleen, leech juice, and pickled newt eyes. The addition of Cowbane is likely crucial for activating or completing the shrinking effect of the potion.

Cowbane is mentioned specifically in the context of Harry Potter's Potions education. During his fifth year, the brewing of a Shrinking Solution was part of the practical portion of the Ordinary Wizarding Level (O.W.L.) exam. In his sixth year, while trying to identify the ingredients of a complex blended potion in Horace Slughorn's class, Harry Potter recalls the recipe for the Shrinking Solution from his exam. He remembers the specific instruction to “add one sprig of cowbane” as one of the final steps, highlighting the detailed knowledge required for even standard school-level Potions. This is its only mention in the original series.

• In the real world, Cowbane (Cicuta maculata) is a highly poisonous plant, also known as water hemlock. Its inclusion as a potion ingredient is consistent with the dangerous nature of many substances used in Potions, where a single misstep can lead to disastrous results.
• In the mobile video game *Harry Potter: Hogwarts Mystery*, Cowbane is an ingredient used in several potions, including the Swelling Solution. This usage is exclusive to the game. (video game)