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|Rafflesia arnoldii flower and bud|
Rafflesia arnoldii is a member of the genus Rafflesia. It is noted for producing the largest individual flower on earth, and a strong odor of decaying flesh - the latter point earning it the nickname of "corpse flower". It is endemic to the rainforests of Borneo and Sumatra. Although there are some plants with larger flowering organs like the titan arum (Amorphophallus titanum) and talipot palm (Corypha umbraculifera), those are technically clusters of many flowers.
Rafflesia arnoldii (Indonesian: padma raksasa) is one of the three national flowers in Indonesia, the other two being the white jasmine and moon orchid. It was officially recognized as a national "rare flower" (Indonesian: puspa langka) in Presidential Decree No. 4 in 1993.
The flower of Rafflesia arnoldii grows to a diameter of around one meter (3 ft) and weighs 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. 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" because of its repulsive odor.
Rafflesia arnoldii is rare and fairly hard to locate. It is especially difficult to locate the flower in forests as the buds take many months to develop and the flower lasts for just a few days. The flowers are unisexual and thus proximity of male and female flowers is vital for successful pollination. These factors make successful pollination a rare event.
When Rafflesia is ready to reproduce, a tiny bud forms on the outside of the root or stem and develops over a period of a year. The cabbage like head that develops, eventually opens to reveal the flower. The stigma or stamen are attached to a spiked disk inside the flower. A foul smell of rotting meat attracts flies and beetles to pollinate. To pollinate successfully, the flies and/or beetles must visit both the male and female plants, in that order. The fruit produced are round lots filled with smooth flesh including many thousands of hard coated seeds that are eaten and spread by tree shrews.
Conservation status 
How many of these plants still survive is unknown, but as the remaining primary forests of Borneo and Sumatra disappear, it can be assumed that their numbers are dwindling. Many are known to be nearing extinction. Some environmentalists are developing ways to recreate the species' environment in an effort to stimulate their recovery. This has proved unsuccessful so far. Steps are also being taken to conserve the forests of Sumatra and Borneo. To help counter the over-collection of this rare plant, residents that have Rafflesia on their private property are encouraged to save the flowers and charge a small fee to see them.
Media related to Rafflesia arnoldii at Wikimedia Commons