Word Study
butterbur
CIDE DICTIONARY
butterbur, n.
A broad-leaved plant (Petasites vulgaris ) of the Composite family, said to have been used in England for wrapping up pats of butter. [1913 Webster]
OXFORD DICTIONARY
butterbur, n. any of several plants of the genus Petasites with large soft leaves, formerly used to wrap butter.
For further exploring for "butterbur" in Webster Dictionary Online