Zea mays has become the very emblem of plenty, with rich golden cobs of corn (maize) overspilling from some of the most effectively farmed arable lands on the planet. Jatropha curcas, on the other hand, is an unprepossessing and indeed toxic plant, better suited to scrubland and hedges. Yet in the world of biofuels, ugly-duckling jatropha has the potential to be, if not a hero, then at least one of the good guys, and a harbinger of better things to come. The goldenheaded siren corn, on the other hand, is inspiring a wrong-headed gold-rush