Rafflesia arnoldii is a species of flowering plant in the parasitic genus Rafflesia within the family Rafflesiaceae. It is native to the rainforests of Sumatra and Borneo.
It is commonly known as the corpse flower or giant padma. The former name comes from its smell being similar to that of decaying flesh. 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 is one of the three national flowers in Indonesia, the other two being the white jasmine (Jasminum sambac) and moon orchid (Phalaenopsis amabilis). It was officially recognised as a national "rare flower" () in Presidential Decree No. 4 in 1993.
Taxonomy
The first European to find Rafflesia was the ill-fated French explorer Louis Auguste Deschamps. He was a member of a French scientific expedition to Asia and the Pacific, detained by the Dutch for three years on the Indonesian island of Java, where, in 1797, he collected a specimen, which was probably what is now known as R. patma. During the return voyage in 1798, his ship was taken by the British, with whom France was at war, and all his papers and notes were confiscated. Joseph Banks is said to have agitated for the return of the stolen documents, but apparently to no avail; they were lost, turned up for sale around 1860, went to the British Museum of Natural History, where they were promptly lost again. They did not see the light of day until 1954, when they were rediscovered at the Museum. To everyone's surprise, his notes and drawings indicate that he had found and studied the plants long before the British. It is thought quite possible the British purposely hid Deschamps' notes, to claim the 'glory' of 'discovery' for themselves. Arnold contracted a fever and died soon after the discovery, the preserved material being sent to Banks. Banks passed on the materials, In the kecamatan ('district') of Pandam Gadang, it is known as cendawan biriang in the Minangkabau language.
Description
Although Rafflesia is a vascular plant, it lacks any observable leaves, stems or even roots, and does not have chlorophyll. It lives as a holoparasite on vines of the genus Tetrastigma, most commonly T. angustifolium. Similar to fungi, individuals grow as a mass of thread-like strands of tissue completely embedded within and in intimate contact with surrounding host cells from which nutrients and water are obtained. It can only be seen outside the host plant when it is ready to reproduce; the only part of Rafflesia that is identifiable as distinctly plant-like are the flowers, though even these are unusual since they attain massive proportions, are reddish-brown with white spots, and stink of rotting flesh. According to Sandved, the flower opens with a hissing sound.
The flower of Rafflesia arnoldii grows to a diameter of around , According to the Mongabay institution, the single largest R. arnoldii to be measured was in width. These flowers emerge from very large, cabbage-like, maroon or dark brown buds typically about wide, but the largest (and the largest flower bud ever recorded) found at Mount Sago, Sumatra in May 1956 was in diameter. Indonesian researchers often refer to the bud as a 'knop' (knob).
According to the Guinness Book of World Records, this is the largest singular flower in the world currently known.
Ecology
Habitat
Rafflesia arnoldii is found in both secondary and primary rainforests.
The only host plant species of R. arnoldii is Tetrastigma leucostaphylum in West Sumatra. Tetrastigma are themselves parasites of a sort, using the strength and upright growth of other surrounding plants to reach the light. The host plants of the host plants – the trees that Tetrastigma uses to climb up to light, are relatively limited in number of species, although they are generally the closest tree to the vine. When it is young, at least at the locations studied in West Sumatra, areas of primary forest, the vine climbs on sapling trees and bushes of Laportea stimulans and Coffea canephora in the undergrowth, in the subcanopy a Campnosperma species is the most important, whereas the only large tree the vine grows in is also Laportea stimulans. Tetrastigma often can completely envelop its host at the subcanopy level, choking out the light to such degree that the forest floor below the canopy is completely dark–this is apparently preferred by Rafflesia arnoldii, as the most knops are found at the darkest locations in the forest. The most common plant associated with Rafflesia arnoldii is the smallish tree Coffea canephora (the well-known robusta coffee), which is actually not native to the area, but was introduced from Africa. It covers most of the undergrowth, with an Importance Value Index (IVI) of over 100%, and is also the main component of the subcanopy with an IVI of 52.74%. The dominant tall tree in these areas is Toona sureni, which has a canopy IVI of 4.97%.
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 stigmas or stamens are attached to a spiked disk inside the flower. A foul smell of rotting meat attracts flies and beetles.The strong odor of decaying flesh produced by Rafflesia arnoldii is a key adaptation for attracting its pollinators. Chemical studies have shown that this scent is caused by sulfur-containing compounds such as dimethyl disulfide and dimethyl trisulfide, which are also present in decomposing organic matter. These compounds attract carrion flies (family Calliphoridae), which serve as the plant’s primary pollinators. The flies are deceived by the odor and coloration of the flower, mistaking it for decaying meat, and in the process transfer pollen between blooms. This highly specialized pollination strategy helps ensure reproduction in the dense rainforests of Sumatra and Borneo. To pollinate successfully, the flies and/or beetles must visit both the male and female plants, in that order. The fruit produced are round berries filled with numerous minute seeds.
The flies Drosophila colorata, Chrysomya megacephala and Sarcophaga haemorrhoidalis visit the late flowers. Black ants of the genus Euprenolepis may feed on the developing flower buds, perhaps killing them.