The fever tree got its name as settlers thought the tree carried a fever which could be caught from it. However the tree grows in swampy areas and on river banks where malaria carrying mosquitos are also found. If you look at a fever tree it will have a dead branch, known as the sacrificial limb. Any poisons or toxins that enter the tree are absorbed into a designated branch.
Medicinally, the roots and a powder made from bark stripped from the trunk are used as an emetic and as a prophylactic against malaria.