The Spectacular Rafflesia

By Farawahida Abu Zaharin, Dzulhelmi Nasir & Suriyanti Su Nyun Pau

Rafflesia is a genus of endophytic, holoparasitic plants, well-known for producing the largest bloom in the world. There are approximately 55 Rafflesia species distributed globally, with 30 species distributed across South-east Asia region, from Thailand through Malaysia, island of Borneo, Sumatra, Java and Philippines. Out of the 30 species, 11 species recorded found in Malaysia. The species natives to peninsular Malaysia are Rafflesia hasseltii, Rafflesia cantleyi, Rafflesia kerii and Rafflesia azlanii. Apart from that, Rafflesia su-meiae found to be the largest flower in peninsular Malaysia. There are also another listed six species found in Sabah and Sarawak. They are Rafflesia arnorldii (Western Sarawak), Rafflesia hasseltii (Samunsam, Sarawak), Refflesia keithii (Sabah, possibly Sarawak), Rafflesia pricei (Sabah & Sarawak), Rafflesia tengku-adlinii (Sabah) and Rafflesia tuan- mudae (Sarawak).

Rafflesia has many vernacular names given by the locals. This include bunga pakma, bunga pecah belah, bunga kobis, bunga akar, kerubut, kekuanga, yak-yak, wusak, tumbuakar, bunga matahari, devil’s betel box, sun mushroom, dai huang hua, monarch flower, sun toadstool, corpse flower, and stinking corpse lily. The members of Rafflesiaceae family are usually dioecious and unisexual. Dioecious refers to an individual plant that produces either a female or male flower. However, 2 species from the Philippines which are Rafflesia baletei and Rafflesia verrucosa are monoaecious, which mean they produced bisexual flowers in one individual plant.

Figure 1: Rafflesia keithii blooms on the first day and last for 3 to 4 days in Poring, Sabah.

The generic name Rafflesia was given to honour Sir Raffles who is the founder of Rafflesia arnoldii (and also the founder of new Singapore). The story begins in 1818, where a British botanist named Dr. Joseph Arnold along with Sir Thomas Stamford Bingley Raffles had collected a gigantic flower found by an unnamed Malay servant during their tour in Bengkulu, Sumatra, Borneo. The name Rafflesia arnoldii is to commemorate the two naturalist and was described for the first time by Robert Brown in 1821. Despite that, the first Rafflesia specimen was actually collected by a French naturalist-surgeon called Louis Auguste Deschamps in 1797. However in 1798, all his works were confiscated when the French expedition ship was captured by the British while returning back to France. Not until 1954, all his papers and notes were rediscovered in the Natural History Museum, London. Since 1821, various Rafflesia species have been named and described by botanist and scientist. Yet, not all of them are recognized and taxonomically resolved. One unidentified species found in unprotected Gumanti Forest, Solok, and another one found in unprotected forest of Pesisir Selatan, Indonesia. To date, much of the flower’s biology remains unknown.

Not all Rafflesia are gigantic but they are definitely the largest blooms in the world. Rafflesia arnorldii recorded as the largest flower species in the world with diameter up to 150 cm and weight about 11 kg. However, the largest bloom of peninsular Malaysia is the 95 cm R. su-meiae. Rafflesia baletei, endemic to Philippines recorded as the smallest flower with approximately 15 cm in diameter. Fascinating facts about the flower is, it is rootless and does not have any leaves. They lack of chlorophyll which is an organelle needed by all green plants (autotroph) to process their own food. Therefore, Rafflesia lives as a parasite to a specific host called lianas, (belong to Tetrastigma sp.) for protection, nutrition and survival.

Figure 2: The bud of Rafflesia keithii needs 6-9 months to full blooms.

Animals such as squirrels, tree shrews, ants, boars and elephant are the dispersal agents of the seeds of Rafflesia. The seeds germinate on the specific host of lianas and penetrate the vines, growing into red bud which looks like a cabbage. The elapse of time for Rafflesia to blooms varies between species: R. arnoldii (67%), R. keithii (75%), R. kerrii (54%), R. pricei (90%) and R. tuan-mudae (80%). The caused might be related with the condition of the host vines, high in humidity and the condition of the soil itself which exposed the bud to predation by rodents, wasp larvae and termites. However, R. cantleyi, R. kerrii, R. keithii, R. pricei and R. tengku-adlinii blooms throughout the year.

The pollinators of Rafflesia flowers are bluebottles and carrion flies. They are basically attracted by the sight of the blooms and its bad odor which similar to rotting flesh.  Pollination in Rafflesia from male anther to female stigma must be very quickly as the blooms do not last very long. Rafflesia arnoldii, for instance blooms perfectly after 7-9 months and can last for 7 days. Rafflesia keithii only blooms after 6-9 months at night and start to deteriorate after three days while R. pricei start to deteriorate after 2 or 3 days and completely turned into black glop by 15 days. Similar to other flowers, after pollination the fruit is formed. Successful pollination will result in a 15 cm fruits that set thousands of seeds. Some of the main factors that contribute to unsuccessful pollination are limited number of individuals, bud die before flourish, male flower and female flower does not blooms simultaneously, unbalanced ratio of male flower and female flower and short anthesis period.

Because of the issues stated in previous paragraph, Rafflesia is said to be a rare, vulnerable life-form. Not only because of its life-span is very short, its blooming factor is totally depends on the presence of host and the occurrence of the pollination. Pollination for Rafflesia is tough as the male and female flower grow on separate plant. To ensure pollination will occur, the male and female plant must blooms at the same time and in close proximity to enables flies pass between them.

Figure 3: Emergence bud of Rafflesia tuan-mudae in Gading National Park, Sarawak.

As a vulnerable plant that only grows on certain species of vine called liana, the Rafflesia are exposed to threats such as ecotourism, commercial logging activities, slash and burns agriculture threats and constructions of highways and hydroelectric dam. Regardless its habitat is being disturbed, locals sought after this flower for its medicinal purposes. We do have conservation in situ programme to protect the Rafflesia but conserving its habitat alone is just not enough. IUCN Categories and Criteria showed that Rafflesia are highly endangered species. One fact that everyone should worry of is that no one has ever cultivate the Rafflesia species.