Results in leeks growing out of the target’s ears. A leek is a vegetable in the onion family.
References from the canon
- During the tension-filled week leading up to the Gryffindor- Slytherin Quidditch match in the spring of 1994, a nasty incident in the corridors resulted in a Gryffindor fourth year and a Slytherin sixth year going to the hospital wing with leeks sprouting out of their ears (PA15).
culinary herb, Old English læc (Mercian), leac (West Saxon) "leek, onion, garlic,"
The Leek is a vegetable related to onions and garlic. According to Welsh legend, King Cadwaladr of Gwynedd ordered his soldiers to wear them on their helmets after fighting a battle with the Saxons in a leek field, and they appear on the helmets of the Welsh Guard in the British Army.
The leek looks something like the description of the magical plant Gurdyroot which Luna Lovegood wanted to share with Ron when he was in the hospital - a large green onion (HBP20).