Picrasma excelsa, commonly known as bitter ash or Jamaican quassia, is a small tree that grows in the Caribbean region and Central and South America. Its bark and wood are used for medicinal purposes due to its bitter taste and energetic properties. There are several synonyms for Picrasma excelsa including Quassia amara, Simaba excelsa, and Picrasma glutinosa. These synonyms are used interchangeably in different regions and by different practitioners. The bitter ash has a long history of use in traditional medicine for treating digestive disorders, fever, and parasites. Its active compounds are thought to be responsible for its therapeutic effects and are still being studied today.