Tree from the cinchona tree ("Cinchona") and was for a long time the remedy of choice for the treatment of malaria. Aspirin was synthesised to replace the sodium salicylate derived from the bark of willow trees ("Salix") which had unpleasant side effects. The anti-cancer drug Paclitaxel is derived from taxol, a substance found in the bark of the Pacific yew ("Taxus brevifolia"). Other tree based drugs come from the paw-paw ("Carica papaya"), the cassia ("Cassia spp."), the cocoa tree ("Theobroma cacao"), the tree of life ("Camptotheca acuminata") and the downy birch ("Betula pubescens"). The papery bark of the white birch tree
Bark painting from Stringybark ("Eucalyptus tetradonta"). The bark must be free of knots and other blemishes. It is best cut from the tree in the wet season when the sap is rising. Two horizontal slices and a single vertical slice are made into the tree, and the bark is carefully peeled off with the aid of a sharpened tool. Only the inner smooth bark is kept and placed in a fire. After heating in the fire, the bark is flattened under foot and weighted with stones or logs to dry flat. Once dry, it is ready to paint upon. Earth pigments—or ochres—in