Quassia amara is a tree native to Suriname, Brazil, and the West Indies. It is a member of the Simaroubaceae family of plants, and its common names include amargo, bitter ash, and bitter wood. This tree is used in herbal medicine to treat digestive disorders, fever, and intestinal worms. It can also be applied topically as an insect repellent.
There are two varieties of the quassia amara tree that are used and cultivated for medicinal purposes. The West Indian type can reach heights of 100 feet (30.5 meters), while the South American variety is smaller, usually around 18 feet (5.5 meters) tall. Both types of trees are deciduous, with smooth gray bark and small flowers that produce black, pea-shaped fruit.The trees are almost never eaten by insects because of the intensely bitter resin in the trees' bark.
It is the bark of the quassia amara tree that is used in herbal and homeopathic medicine. Generally the bark is sold in ground-up chips and used to produce tonic or tinctures. The tonics and tinctures are generally made by steeping the bark in cold water for extended periods of time. The tree's resin is among the most bitter substances on earth, so it can also be used to flavor liqueurs, jams, and puddings. Fine shavings of quassia amara bark might also be used like hops to brew beer and ale.
This tree has been used for centuries to treat a variety of stomach and digestive ailments. Quassia amara tonics settle nausea and reduce acids in the stomach that cause indigestion and heartburn. It is often given to people recovering from illness to increase their appetites, although taken in larger amounts it can have a laxative effect. The bark is also an effective fever reducer and can be used in place of quinine to treat malaria outbreaks. In modern herbal medicine, quassia amara is used as a tincture to improve digestion and liver function.
Quassia amara is also effective against many types of insects and parasites. It is a vermifuge, which means that it kills and helps expel parasitic intestinal worms like threadworms and roundworms. As a hair rinse, it can reduce dandruff and was once a common treatment for head lice. It can be mixed into lotions to make a topical insect repellent, and quassia amara teas can also be sprayed onto plants as a natural insect repellent and pesticide.