I agree with your observation but not your conclusion.

The fever tree (Koorsboom in Afrikaans)(Acacia xanthophloea) grows mainly in depressions and shallow pans where underground water is present or surface water collects after summer rains. It is also found in low-lying swampy areas, along the margins of lakes and on river banks. Early pioneers noticed that some of their parties contracted very bad fevers … Continue reading I agree with your observation but not your conclusion.