Fraoch, or heather ale, is a legendary unhopped beer from Scotland, said to date back to Pictish times.
Gentiana lutea (and related species), a fantastically bitter plant which should be added to beer only in very small quantities. “Gentian root is a common beverage flavouring for bitters. The soft drink Moxie contains gentian root. The French liqueur Suze is made with gentian. Americano apéritifs contain gentian root for bitter flavoring. It is an ingredient in the Italian liqueur Aperol. It is also used as the main flavor in the German after-dinner digestif called Underberg, and the main ingredient in Angostura bitters and Peychaud’s Bitters.” Thank you, Wikipedia.