Natural rubber derived from latex had long been a curiosity. When Nelson Goodyear perfected his method of vulcanisation of rubber and showcased its applications at the Great Exhibition of 1851 the possibilities now seemed endless. But by 1860 demand was outstripping supply from Brazil. Kathy Willis examines how Kew was charged with getting seeds of this economically vital plant out of South America to germinate at Kew Gardens, and then to send seedlings off to cultivate in far flung reaches of the Empire. The historian Emma Reisz explains how Kew acted as the international clearing house for smuggled seeds out of Brazil. Historian Jim Endersby sheds light on why Kew put its faith in one man: Henry Wickham, a travelling plant hunter with dubious botanical credentials. We hear from Mark Nesbitt, curator of Kew's economic botany collection, on how, despite rubber being recognised as an economically essential plant for the British Empire's economy, the whole business of transporting and nurturing the seedlings turned out to be a comically hit and miss affair. Producer Adrian Washbourne.