Rafflesia arnoldii

Appearance

The flower of ''Rafflesia arnoldii'' grows to a diameter of around one meter, but the greatest measurement from a reliable source is 105 centimeters for one at Palupah Nature Reserve near Bukittinggi, Sumatra measured by Prof. Syabuddin of Andalas University.

R. arnoldi weighs up to 11 kilograms. These flowers emerge from very large, cabbage-like, maroon or magenta buds typically about 30 cm wide, but the largest found at Mount Sago, Sumatra in May 1956 was 43cm in diameter.

''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.

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.

Behavior

It lives as a parasite on several vines of the genus ''Tetrastigma'', which grow only in primary rainforests.

Reproduction

''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 outside the root or stem of its host 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 treeshrews.