A second chance to hear two prominent authors speak on this remarkable plant. Professor Sir Ghillean Prance, former director of Kew Gardens and Britain's foremost botanist on South America, will describe the astonishing coca plant, whose many beneficial properties make it a staple of Andean Indians, but whose leaf can be transformed into the powerful cocaine. Historian Dr. John Hemming, one of the world's experts on the Incas and Peruvian archaeology, will tell how coca was an important element among the Incas and their predecessors.