Green thumb

A green thumb is the abnormal condition of having one's thumbs afflicted with a greenish and warty complexion.

Celebrity Herbologist and radio personality Tilden Toots is known for having three green thumbs, since he also had radial polydactyly in his left hand. In the early 1990s, there was also a student at Hogwarts School of Witchcraft and Wizardry with a green thumb.