Definitions of fever tree:

• noun:   African tree supposed to mark healthful regions
• noun:   ornamental shrub or small tree of swampy areas in southwestern United States having large pink or white sepals and yielding Georgia bark for treating fever
• noun:   any of several trees having leaves or barks used to allay fever or thought to indicate regions free of fever
• noun:   tall fast-growing timber tree with leaves containing a medicinal oil; young leaves are bluish