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 bread bark is the only part of a tree trunk that is actually edible, the remaining bark and wood is made up of cellulose which animals, including humans, cannot digest. The dried and ground inner bark was added in proportions like 1/4th to 1/3rd "bark flour" to the remaining grain flour. Erik Pontoppidan, the Bishop of Bergen, Norway, in the mid 18th century, recommended using elm, as it helped the often crumbly bark bread hold together better. The bark will, however, add a rather bitter taste to the bread, and give particularly white bread an unappetizing grey-green hue. Another problem is