The fever tree is an attractive, semi-deciduous to deciduous tree approximately 15 to 25 meters tall and has an open, rounded to spreading or flattish crown which is sparsely foliated. The characteristic, almost luminous, lime green to greenish-yellow bark is smooth, slightly flaking, and coated in a yellow powdery substance described by some as sulphurous. If the powdery surface is rubbed away with the finger it will reveal a green bark beneath. Young twigs have a red-brown bark which peels off leaving the twigs sulphur yellow. The long straight white thorns are arranged in pairs and although they are very significant on young trees they often become barely noticeable on mature specimens