dandelion
There are two stories behind this word. The first is the word itself which comes from 15th century French 'dent de lion' or 'lion's tooth' because of the tooth-like shape of its leaves. Secondly, it has long been known to be a diuretic, a medical term meaning that it causes the body to urinate. In French, it is actually known as 'pisse en lit' (Wet the bed!)