Quassia Bark comes from the plant Quassia amara, an evergreen shrub from the tropics of South America with broadly winged leaves and vivid crimson flowers. The name “amara” means “bitter” in Latin and describes the plant’s extremely bitter taste. The bitter principle found in Quassia Bark and wood is used in Angostura Bitters, which is used for flavoring in soft drinks, digestive tonics and cocktails. Medically, Quassia amara is used as a digestive and to treat fever.