Cinchona ledgeriana" had a yield of 8 to 13 percent quinine in bark grown in Dutch Indonesia which effectively out-competed the British Indian production. It was only later that the English saw the value and sought to obtain the seeds of "C. ledgeriana" from the Dutch. During World War II, the Japanese conquered Java and the United States lost access to the cinchona plantations that supplied war-critical quinine medication. Botanical expeditions – called Cinchona Missions – were launched in 1942-1944 to explore promising areas of South America in an effort to locate cinchona species that contained quinine and could be harvested
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