Largest Flower In The World Rafflesia arnoldii (corpse flower)

A rare, parasitic, rootless and leafless plant, Rafflesia arnoldii has the largest known flower in the world.
  
About this species
This southeast Asian plant has the largest known individual flower in the world. It is parasitic on members of the genus Tetrastigma (in the grape family,Vitaceae). It has no roots or leaves and most of the time lives unobserved inside the woody stems and roots of its host. Rafflesia arnoldii only becomes visible when its plump buds emerge through the bark of its host and develop into the large, fleshy flowers which are pollinated by carrion-flies.