Brewer's plant is a term used to refer to the HOP plant, which is a perennial climbing plant that is widely cultivated for its flowers and used in the production of beer. The HOP plant is an essential ingredient in beer, as it provides bitterness, flavor, and aroma. It is also used as a preservative and stabilizer. The HOP plant is a member of the Cannabaceae family and is native to Europe and parts of Asia.