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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. It is noted for producing the largest individual flower on Earth. There are plants with larger flowering organs like the titan arum (Amorphophallus titanum) and talipot palm (Corypha umbraculifera); however, those are 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).

In 1818, the British surgeon Joseph Arnold collected a specimen of another Rafflesia species found by a Malay servant in a part of Sumatra, then a British colony called British Bencoolen (now Bengkulu), during an expedition run by the recently appointed Lieutenant-Governor of Bencoolen, Stamford Raffles. Apparently aware of Jack's work, Brown finally had the article published in the Transactions of the Linnean Society a year later, formally introducing the name R. arnoldii (he ignores Jack's work in his article). Because Jack's name has priority, R. arnoldii should technically be a synonym of R. titan, but at least in Britain, it was common at the time to recognise the names introduced by well-regarded scientists such as Brown, over what should taxonomically be the correct name. Instead of sinking R. arnoldii into synonymy, however, he declared that the name R. titan was "incompletely known": the plant material used by Jack to describe the plant has been lost. Mabberley also pointed out that the genus Rafflesia was thus first validated by an anonymous report on the meeting published in the Annals of Philosophy in September 1820 (the name was technically an unpublished nomen nudum until this publication).

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. The flower of Rafflesia arnoldii grows to a diameter of around 1 m (3 ft 3 in), and weighs up to 11 kg (24 lb).

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 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. Other important components of the ecosystem around Rafflesia arnoldii plants at this location are, in the undergrowth, the Urticaceae Laportea stimulans (IVI: 55.81%) and Villebrunea rubescens (IVI: 50.10%), as well as the wild cinnamon Cinnamomum burmannii (IVI: 24.33%) and the fig Ficus disticha (IVI: 23.83%). In the subcanopy the main plants are Toona sureni (IVI: 34.11%), Laportea stimulans (IVI: 24.62%), Cinnamomum burmannii (IVI: 18.45%) and Ficus ampelos (IVI: 14.53%). Rafflesia arnoldii has been found to infect hosts growing in alkaline, neutral and acidic soils.

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.

It has not been assessed for the IUCN Red List, but the conservation status of the Rafflesia arnoldii is currently of concern due to anthropogenic and biological factors.

Quick Facts

• 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).
• The flower of Rafflesia arnoldii grows to a diameter of around 1 m (3 ft 3 in), and weighs up to 11 kg (24 lb).
• Rafflesia arnoldii is found in both secondary and primary rainforests.
• It is native to the rainforests of Sumatra and Borneo.
• The only host plant species of R. arnoldii is Tetrastigma leucostaphylum in West Sumatra.

Source material: Wikipedia - "Rafflesia arnoldii". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.