Cinchona genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (antifever) agent especially useful in treating malaria. Cinchona alkaloids include: They find use in organic chemistry as organocatalysts in asymmetric synthesis. Alongside the alkaloids, many cinchona barks contain cinchotannic acid, a particular tannin, which by oxidation rapidly yields a dark-coloured phlobaphene called red cinchonic, cinchono-fulvic acid or cinchona red. In 1934, efforts to make malaria drugs cheap and effective for use across countries led to the development of a standard called "totaquina" proposed by the Malaria Commission of the League of Nations.
Bark (botany) ridges. In the cork oak ("Quercus suber") the bark is thick enough to be harvested as a cork product without killing the tree; in this species the bark may get very thick (e.g. more than 20 cm has been reported). Some barks can be removed in long sheets; the smooth surfaced bark of birch trees has been used as a covering in the making of canoes, as the drainage layer in roofs, for shoes, backpacks etc. The most famous example of using birch bark for canoes is the birch canoes of North America. The inner bark (phloem) of some trees