Rafflesia.  

The flower of Rafflesia arnoldii grows to a diameter of around one meter (3 ft) and weighing up to 11 kilograms (24 lb). It lives as a parasite on the Tetrastigma vine, which grows only in primary (undisturbed) rainforests. Rafflesia lacks any observable leaves, stems or even roots, yet is still considered a vascular plant. Similar to fungi, individuals grow as thread-like strands of tissue completely embedded within and in intimate contact with surrounding host cells from which nutrients and water are obtained. This plant produces no leaves, stems or roots and does not have chlorophyll. It can only be seen when it is ready to reproduce. Perhaps the only part of Rafflesia that is identifiable as distinctly plant-like are the flowers; although, even these are unusual since they attain massive proportions, have a reddish-brown coloration and stink of rotting flesh, which is why it was nicknamed the "corpse flower". This scent attracts insects such as flies which then pollinate the rare plant. It is not to be confused with the Titan Arum, Amorphophallus titanum, which is also commonly referred to as the "corpse flower".