Amorphophallus titanum (meaning "misshapen phallus titan") is a massive flower and is in fact the largest unbranched flower in the world. The colloquial name "Corpse Flower" comes from an odour given off by the flower which smells distinctly of decomposing flesh. This rotting smell attracts flies and therefore aids in cross pollination.
This flower grows only in the rain forests of Sumatra and holds the record for tallest flower in the world, having been cultivated to the height of 3.1 M!
Watch this clip from David Attenborough's Private Life of Plants to see the first footage of Amorphophallus titanum pollination ever.