Rafflesia


Rafflesia, or stinking corpse lily, is a genus of parasitic flowering plants in the family Rafflesiaceae. The species have enormous flowers, the buds rising from the ground or directly from the lower stems of their host plants; one species has the largest flower in the world. Plants of the World Online lists up to 41 species from this genus; all of them are found in Southeast Asia.
Western Europeans first learned about plants of this genus from French surgeon and naturalist Louis Deschamps when he was in Java between 1791 and 1794; but his notes and illustrations were seized by the British in 1798 and were not available to Western scientists until 1861. The first British person to see one was Joseph Arnold in 1818, in the Indonesia rainforest in Bengkulu, Sumatra, after a Malay servant working for him discovered a flower and pointed it out to him. The flower, and the genus, was later named after Stamford Raffles, the leader of the expedition and the founder of the British colony of Singapore.
The following is from Arnold's account of discovering the flower:
Vivid contemporary accounts documenting some of the most inaccessible species of Rafflesia are described in the popular science book, Pathless Forest: The Quest to Save the World's Largest Flowers, by botanist Chris Thorogood based at the University of Oxford Botanic Garden.

Description

The plant has no stems, leaves or roots. It is a holoparasite of vines in the genus Tetrastigma, spreading its absorptive organ, the haustorium, inside the tissue of the vine. The only part of the plant that can be seen outside the host vine is the five-petalled flower. In some species, such as Rafflesia arnoldii, the flower may be over in diameter, and weigh up to. A Rafflesia that bloomed in West Sumatra in January 2020 was measured to be in diameter, the largest flower ever recorded— wider than the flower reported as the largest in 2017. Even one of the smallest species, R. baletei, has diameter flowers. A team of morphologists and geneticists headed by Prof. Charles Davis of Harvard has discovered an important difference between Rafflesia spp. and the very similar Sapria spp. In both genera the petals are now described as sepals instead of vaguely defined "perigon lobes". In Sapria, the "diaphragm" is a true corona while in Rafflesia the diaphragm is made up of adnate petals to form a dome, the true corona being greatly reduced and fused with the adnate petals.
The flowers look and smell like rotting flesh. The foul odour attracts insects such as carrion flies, which transport pollen from male to female flowers. Most species are dioecious, having separate male and female flowers, but a few have hermaphroditic flowers. Little is known about seed dispersal. Tree shrews and other forest mammals eat the fruits. The extremely tiny seeds have extremely tiny elaiosomes, and are thus most likely dispersed by ants. The seeds are packed into berries, each of which contains hundreds of thousands of seeds.
Because Amorphophallus has the world's largest unbranched inflorescence, it is sometimes mistakenly credited as having the world's largest flower. Both Rafflesia and Amorphophallus are flowering plants, but they are unrelated to each other. Rafflesia arnoldii has the largest single flower of any flowering plant, at least in terms of weight. Amorphophallus titanum has the largest unbranched inflorescence, while the talipot palm forms the largest branched inflorescence, containing thousands of flowers; the talipot is monocarpic, meaning the individual plants die after flowering.
Rafflesia are also remarkable for showing a large horizontal transfer of genes from their host plants. This is well known among bacteria, but not higher organisms. It occurs in the mitochondria found within the cells of Rafflesia; these appear to have exchanged genes with the mitochondria of the host tissue.

Names

In Indonesian and Malaysian, it is known as padma. The species R. arnoldii is known as padma raksasa. In Javanese it is called patma. In Malay, the 'normal' R. hasseltii is vernacularly known as pakma, patma or ambai-ambai, whereas the goliath R. arnoldii from Sumatra is called krubut or kerubut, 'great flower'. The words padma, pakma or patma originate etymologically from the word पद्म, Sanskrit for 'lotus'.
In English, Rafflesia is known as the stinking corpse lily. It is also known as "corpse flower", or bunga bangkai in Indonesian, a name that more commonly refers to the titan arum of the family Araceae. The type species arnoldii has been called the "monster flower".

Taxonomy

introduced the genus Rafflesia to the wider scientific world in a presentation before the Linnean Society of London in June 1820, but his scientific paper on the subject was only published in late 1821.
In 1999, the British botanical historian David Mabberley pointed out that the genus Rafflesia was first validated by an anonymous report on the meeting published in the Annals of Philosophy in September 1820. Mabberley claimed the author was Samuel Frederick Gray. However, as that is nowhere stated in the Annals, per Article 46.8 of the code of ICBN, Mabberley was wrong to formally ascribe the validation to Gray. The validation of the name was thus attributed to one Thomas Thomson, the editor of the Annals in 1820, by the IPNI. Mabberley admitted his error in 2017. This Thomson was not the botanist Thomas Thomson, who was three years old in 1820, but his identically named father, a chemist.

Evolution and phylogeny

Comparison of mitochondrial DNA sequences of Rafflesia with other angiosperm mtDNA indicated this parasite evolved from photosynthetic plants of the order Malpighiales. Another 2004 study confirmed this result using both mtDNA and nuclear DNA sequences, and showed the three other groups traditionally classified in Rafflesiaceae were unrelated. A 2007 study more specifically found Rafflesia and its relatives to be embedded within the family Euphorbiaceae as traditionally circumscribed, which was surprising, as members of that family typically have very small flowers. According to their analysis, the rate of flower size evolution was more or less constant throughout the family except at the origin of Rafflesiaceae, where the flowers rapidly evolved to become much larger before reverting to the slower rate of change.
To maintain monophyletic families, in 2016 the APG IV system separated the family Peraceae from the Euphorbiaceae. A summary cladogram is shown below, with family placements in the APG IV system.
A 2010 molecular phylogenetic study of 18 species of Rafflesia found that they fell into four clear-cut geographically defined groups:
However, the clear monophyly of the four geographical clades does not correspond to any clear difference in appearance. There is no consistency within the clades in the size of flowers, or the presence or absence of white warts; species in different clades resemble one another more than they do some other species within the same clade. Homoplasy – repeatedly gaining or losing traits – seems to be the rule within Rafflesia.

Accepted species

, Plants of the World Online accepted the following species:
  • Rafflesia arnoldii – Sumatra, Borneo
  • Rafflesia aurantia – Philippines
  • Rafflesia azlanii – Peninsular Malaysia
  • Rafflesia baletei – Philippines
  • Rafflesia banaoana Malabrigo – Philippines ; treated as a synonym of R. leonardi by other sources
  • Rafflesia bengkuluensis – Sumatra
  • Rafflesia borneensis Koord. – Indonesian Borneo
  • Rafflesia camarinensis F.B.Valenz., Jaucian-Adan, Agoo & Madulid – the Philippines
  • Rafflesia cantleyi – Peninsular Malaysia
  • Rafflesia ciliata Koord. – Indonesian Borneo
  • Rafflesia consueloae – Philippines
  • Rafflesia gadutensis – Sumatra
  • Rafflesia hasseltii – Sumatra
  • Rafflesia horsfieldii R.Br. – West Java
  • Rafflesia keithii – Borneo
  • Rafflesia kemumu Susatya, Hidayati & Riki – Sumatra
  • Rafflesia kerrii – Thailand, Peninsular Malaysia
  • Rafflesia lagascae – Philippines
  • Rafflesia lawangensis – Sumatra
  • Rafflesia leonardi – Philippines
  • Rafflesia lobata – Philippines
  • Rafflesia manillana – Philippines
  • Rafflesia meijeri Wiriad. & Sari – North Sumatra, Indonesia
  • Rafflesia micropylora – Sumatra
  • Rafflesia mira – Philippines
  • Rafflesia mixta – Philippines
  • Rafflesia parvimaculata Sofiyanti, K.Mat-Salleh, Khairil, Zuhailah, Mohd.Ros. & Burs – Peninsular Malaysia
  • Rafflesia philippensis – Philippines
  • Rafflesia pricei – Borneo
  • Rafflesia rochussenii – Java, Sumatra
  • Rafflesia schadenbergiana – Philippines
  • Rafflesia sharifah-hapsahiae J.H.Adam, R.Mohamed, Aizat-Juhari & K.L.Wan – Peninsular Malaysia
  • Rafflesia speciosa – Philippines
  • Rafflesia su-meiae M. Wong, Nais & F.Gan – Peninsular Malaysia
  • Rafflesia tengku-adlinii – Borneo
  • Rafflesia tiomanensis Siti-Munirah, Salamah & Razelan – Pulau Tioman, Peninsular Malaysia
  • Rafflesia tuan-mudae – Borneo
  • Rafflesia tuanku-halimii J.H.Adam, Aizat-Juhari, Azilah & K.L.Wan – Peninsular Malaysia
  • Rafflesia verrucosa – Philippines
  • Rafflesia witkampii Koord. – Indonesian Borneo
  • Rafflesia zollingeriana Koord. – East Java

    Other names

  • Rafflesia patma – Java; considered a synonym of R. horsfieldii by Plants of the World Online, apparently based on the confused writings of a British historian of botany, although R. horsfieldii, for which no specimens were ever collected, only a drawing made which was lost centuries ago, is not considered a valid taxon by Rafflesia experts.
  • Rafflesia titan – A synonym of R. arnoldii; it was in fact validly published earlier, being rushed to publication in Singapore in 1820 by a British botanist who feared that the French, who had actually discovered a species before the British, might deny the glory of the species description to servants of the British Empire. In order to retain the honour of naming the species to the famous British scientist Robert Brown, the historian of botany mentioned above chose to pretend a 1821 pre-print Brown sent to a colleague was a valid 'effective publication', which has been accepted by the relevant British institutions.