Trial and error
Local doctor
Watching animals
plants
herbs
lichens
all of these are studied by botanists
20
40
60
80
Aspirin
Willow Bark
Both of these.
Neither of these.
Willow
Artemisia Annua
Curare
Cranberry
100
200
300
400
Sweet Annie
Dandelion
mountain tops
jungles
oceans
your back yard
everywhere
25
50
75