Rafflesia arnoldii


Southeast Asia: Home of Rafflesia sp

The most extraordinary of all parasitic plants lives inside its host and only makes itself visible when it brings up the biggest of all flowers in the plant kingdom. Rafflesia arnoldii is an endemic plant that occurs only in the rainforest of Bengkulu in Sumatra Island, Indonesia. It is a parasitic plant that lives inside the body Tetrastigma vine that is usually found hanging from tropical trees, in undisturbed forests mostly. On some occasions, and in places where the vine spreads itself on the ground, a growth starts to develop on its bark. It grows for several weeks until it bursts and appears like a big closed orange cabbage with its leaves tightly closed and supported on a small woody calyx grown by the vine. One night, those leaves open and show themselves as five enormous leathery orange petals mottled with cream patches like warts. These petals form an enormous corolla that can be as large as 100 cm in diameter, all around a deep calyx where a central disk is placed on top of a column. The disc is covered with many long thick spines called processes. Underneath them all around the disc are sexual organs of the flower. Male and female flowers grow on separate individuals, thus Rafflesia plants are called dioecious plants. The whole flower can weigh as much as 10 kg. Thomas Stanford Raffles, the founder of Singapore, and when governor of a small British Colony in the island of Sumatra, was the first European who described this amazing plant. This plant, as all the other similar but smaller 28 species of its genus, is named after him. All Rafflesiaspecies are found on the Malay Peninsula, Borneo and Sumatra islands, Thailand and the Philippines.


An Elusive Yet Successful Flower

 The vine species of the genus Tetrastigma can be easily found in the same region, in Sumatra islandwhich makes it harder to find Rafflesia plants as it hard to distinguish those that are infected from normal uninfected plants. We can only tell that the vines are infected when Rafflesia plants show their buds growing on the soil following the vine stems. The buds themselves can grow very slowly and even at full size they can be closed for many days until the flower finally opens at night. This way, a vast majority of buds are likely to be damaged by animals or even rot before they open. Some locals call Rafflesia plants corpse flowers, due to their pungent smell like rotting meat. However, the smell, although strong, it does change throughout the flower short life after it is open and it does not always resemble rotting meat of a carcass. The female flower is pollinated by small flies attracted by its strong and sometimes stinky smell. The flies land on the disk and crawls down to its base densely covered with long dark red hairs. In on their turn, such a crowd of flies attracts their predators like spiders which are seen buildings their webs inside Rafflesia flowers frequently. The flower usually last up to 3 to 4 days after which it decays rapidly becoming a black viscous mass. Female flowers are rarer than masculine flowers which makes their pollination a rare event seldom seen on those forests.


An Enigma of Survival

The elusive appearance of Rafflesia fruits lying on the forest floor proves it. The fruit is a brown sphere of about 15 cm in diameter, with a rough and woody skin. Its creamy pulp full of dark red seeds attracts shrews and squirrels as the plants main seed dispersers. However, how the seeds germinate and find their way into a host vine is still a mystery. Also unknown so far is the reason for such a big and disproportionate flower compared to the rest of the Rafflesia plant body, which practically resumes to a tread of tissue inside the vine’s stem. It is considered that big and publicizing flowers results from competition among plant species for the attention and services of pollinators. However, in the case of Rafflesia species that seems unlikely as in their habitat pollinators are far from being scarce. Plants like life itself are limited by profitable budgets. The energy that they spend on producing elaborate flowers, leaves or any other organ must, under normal conditions, bring them some sort of useful advantage. It seems however that Rafflesia species have turn out to be less restricted. In fact they do not have any effort in obtaining food; they get it all from the host. As such, and as long as the host is healthy, Rafflesia indulges itself putting no limits on the amount of energy and nutrients that is needed on producing such an astounding flower. Thus, it seems that we have the ultimate parasite in which its success, based on almost no effort, lead to prodigality. 

Southeast Asia: Home of Rafflesia sp.