Rafflesia is a genus of parasitic flowering plants. It contains approximately 27 species (including four incompletely characterized species as recognized by Willem Meijer in 1997), all found in southeastern Asia, on the Malay Peninsula, Borneo, Sumatra, and the Philippines.
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 an endoparasite 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" (but see below). The vile smell that the flower gives off 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 bisexual flowers. Little is known about seed dispersal. However, tree shrews and other forest mammals apparently eat the fruits and disperse the seeds.
Rafflesia is an official state flower of Indonesia, also Sabah state in Malaysia, as well as for the Surat Thani Province, Thailand.
The name "corpse flower" applied to
Rafflesia is 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 still distantly related.
Rafflesia arnoldii has the largest
single flower of any flowering plant, at least when one judges this by weight.
Amorphophallus titanum has the largest
unbranched inflorescence, while the Talipot palm (
Corypha umbraculifera) forms the largest
branched inflorescence, containing thousands of flowers; this plant is monocarpic, meaning that individuals die after flowering.
Comparison of mitochondrial DNA (mtDNA) sequences of
Rafflesia with other angiosperm mtDNA indicated that this parasite evolved from photosynthetic plants of the order Malpighiales.. Another study from that same year confirmed this result using both mtDNA and nuclear DNA sequences, and showed that three other groups traditionally classified in Rafflesiaceae were unrelated. 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. 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.
Source:
Wikipedia 
