Visitors are treated to an extremely rare sight at the Chicago Botanic Garden in Chicago, Illinois, on Friday - the blooming of two corpse flowers. It is unusual enough to see one of nature's biggest, rarest, not to mention smelliest, flowers bloom, because it generally happens only fleetingly once every five to 10 years. But it is extraordinary to see two bloom at once. That is why the two 2.1m-tall corpse flowers have attracted thousands this week, who are willing to put up with the smell of rotting flesh that they emit to attract pollinating beetles and flies.