Rafflesia

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Rafflesia
Rafflesia sumatra.jpg
Rafflesia arnoldii flower and bud
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Malpighiales
Family: Rafflesiaceae
Genus: Rafflesia
R.Br.
Species

See text.

Rafflesia is a genus of parasitic flowering plants. It contains approximately 28 species (including four incompletely characterized species as recognized by Willem Meijer in 1997), all found in southeastern Asia, on Indonesia, Malaysia, Borneo, Sumatra, Thailand and the Philippines.[1]

Rafflesia was found in the Indonesian rain forest by an Indonesian guide working for Dr. Joseph Arnold in 1818, and named after Sir Thomas Stamford Raffles, the leader of the expedition. It was discovered even earlier by Louis Deschamps in Java between 1791 and 1794, but his notes and illustrations, seized by the British in 1803, were not available to western science until 1861.[citation needed]

The plant has no stems, leaves or true roots. It is a holoparasite of vines in the genus Tetrastigma (Vitaceae), 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-petaled flower. In some species, such as Rafflesia arnoldii, the flower may be over 100 centimetres (39 in) in diameter, and weigh up to 10 kilograms (22 lb). Even the smallest species, R. baletei, has 12 cm diameter flowers. The flowers look and smell like rotting flesh, hence its local names which translate to "corpse flower" or "meat flower" (see below). The foul odor attracts insects such as flies, which transport pollen from male to female flowers. Most species have separate male and female flowers, but a few have hermaphroditic flowers. Little is known about seed dispersal. However, tree shrews and other forest mammals eat the fruits and disperse the seeds. Rafflesia is the official state flower of Indonesia, the Sabah state in Malaysia, and of the Surat Thani Province, Thailand.

The name "corpse flower" applied to Rafflesia can be confusing because this common name also refers to the titan arum (Amorphophallus titanum) of the family Araceae. Moreover, 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 only distantly related. Rafflesia arnoldii has the largest "single" flower of any flowering plant, at least in terms of weight. A. titanum has the largest "unbranched" inflorescence, while the talipot palm (Corypha umbraculifera) forms the largest "branched" inflorescence, containing thousands of flowers; the talipot is monocarpic, meaning the individual plants die after flowering.

Classification[edit]

Rafflesia keithii bloom, approximately 80 cm in diameter
R. kerrii flower
Three Rafflesia pricei growing in close proximity near Mount Kinabalu, Sabah, Malaysia
New hypothesis of Rafflesiaceae derived from within Euphorbiaceae: Rafflesiaceae in red, Euphorbiaceae in black (redrawn from Davis et al., 2007)
Species
Unverified species

Comparison of mitochondrial DNA (mtDNA) sequences of Rafflesia with other angiosperm mtDNA indicated this parasite evolved from photosynthetic plants of the order Malpighiales.[2] Another study from that same year confirmed this result using both mtDNA and nuclear DNA sequences, and showed the three other groups traditionally classified in Rafflesiaceae were unrelated.[3] A more recent study found Rafflesia and its relatives to be embedded within the family Euphorbiaceae, which is surprising, as members of that family typically have very small flowers.[4] 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.

Malaysian species[edit]

Species native to Malaysia include Rafflesia arnoldii, Rafflesia cantleyi, Rafflesia hasseltii, Rafflesia keithii, Rafflesia kerrii, Rafflesia pricei, and Rafflesia tengku-adlinii. R. arnoldii boasts the world's largest single bloom. Some endemic Malaysian species, such as R. keithii, begin blooming at night and start to decompose only two to three days later. The time from bud emergence to flowering is six to nine months. Male and female flowers must be open simultaneously for pollination to occur, hence successful pollination and fruit production are quite rare. In addition to habitat loss, these reproductive limitations are contributing factors to why many species are endangered. R. keithii is found along the eastern slopes of Mount Kinabalu in the Lohan Valley of Sabah.[1] Rafflesia tuan-mudae is endemic to only Gunung Gading National Park in Sarawak.

Loss of the chloroplast genome[edit]

Research published in the journal Molecular Biology and Evolution (January 2014)[2] reveals that one Philippine Rafflesia species from the island of Luzon, R. lagascae (formerly described as R. manillana) has lost the genome of its chloroplast and it is speculated that the loss happened due to the parasitic lifestyle of the plant. This discovery makes Rafflesia the first land plant without a chloroplast genome, which had once thought to be impossible. [3][4]

See also[edit]

References[edit]

  1. ^ a b VJR Rafflesia Reserve, Forestry Department Sabah, Malaysia, [1]
  2. ^ Barkman, T. J.; S.-H. Lim, K. Mat Salleh, J. Nais (January 20, 2004). "Mitochondrial DNA sequences reveal the photosynthetic relatives of Rafflesia, the world's largest flower". PNAS 101 (3): 787–792. doi:10.1073/pnas.0305562101. PMC 321759. PMID 14715901. 
  3. ^ Nickrent, D. L.; A. Blarer, Y.-L. Qiu, R. Vidal-Russell, F. E. Anderson. (October 20, 2004). "Phylogenetic inference in Rafflesiales: the influence of rate heterogeneity and horizontal gene transfer". BMC Evolutionary Biology 4: 40. doi:10.1186/1471-2148-4-40. PMC 528834. PMID 15496229. 
  4. ^ Davis, C. C.; M. Latvis, D. L. Nickrent, K. J. Wurdack, D. A. Baum (January 11, 2007). "Floral gigantism in Rafflesiaceae". Science 315 (5820): 1812. doi:10.1126/science.1135260. PMID 17218493. 

Further reading[edit]

External links[edit]