Rafflesia arnoldii, The Largest Flower in the World

Rafflesia arnoldii (Stinking Corpse Lily), The Giant Flower
Rafflesia arnoldii (Stinking Corpse Lily), The Giant Flower

Well, Rafflesia arnoldii, the largest flower in the world, does not need to force the viewer to stand in front of it in awe, because this happens spontaneously.

And it happens not only for the inconceivable for the flower universe its astronomical size, which often exceeds 1 meter, nor for its unusual shape that look more like a mushroom, but even not even for its awful stench, which crushing the idea that flowers in general present, that is, neither more nor less fragrant: the awe in front of it is born from the tangible proof that this world of Cartesian reality still has a fairytale dimension, almost dreamy.

However, this unique flower belongs to a plant that in turn belongs to a genus composed entirely of very particular parasitic species. The peculiarity of the plants of the genus Rafflesia will be presented later in the text below.

However, one aspect of it can not be missing from this miserable literary introduction: it is the carrion flies – the exclusive pollinators of flowers.

Where, although these carrion flies perform, whether they like it or not, the important work of pollination, in return they get nothing substantial from Rafflesia arnoldii, proving in the most scientific way the enormous functional value of all kinds of suckers.

On the other hand, of course, without the suckers, it is almost certain that this world of Cartesian reality could indeed take on a fairytale dimension, almost dreamy.

Inside the flower of Stinking Corpse Lily, there is as a continuation of the floral axis the disk, which has thorny type protrusions on it, the presence of which remains unexplained.

The Disc with the Thorny Shape Protrusions Inside the Flower of Stinking Corpse Lily
The Disc with the Thorny Shape Protrusions Inside the Flower of Stinking Corpse Lily
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What are Raflesias

Rafflesias form a genus of plants which are characterized as obligate – holoparasitic, since they can not complete their biological cycle without the presence of a host, and at the same time they are unable to photosynthesize as they lack chlorophyll molecules.

Driven perhaps by feelings of gratitude, it is extremely rare for them to kill the plant in which they are parasitized (some species of the genus Tetrastigma), and in which they go through all the phases of their life except those of their sexual reproduction, fruiting and dispersal.

In the host they develop as fully integrated filamentous tissues, which come in direct contact with the cells that surround them, supplied by these the necessary nutrients and water. Their presence outside the host becomes apparent only from the stage of development of the flower bud onwards.

Their mushroom-like flowers are generally large in size, while that of Rafflesia arnoldii in particular is recognized as the largest simple flower of angiosperms – assuming that the Rafflesias belong to them, a fact for which serious scientific doubts are raised – as it can reach a diameter of 1.5 m. Also, all the flowers are unisexual (dioecious) and are distinguished for the irresistible "fragrance" that diffuses from them, olfactory reminiscent, sometimes more and sometimes less, decaying flesh. This stench unhesitatingly attracts the most likable carrion flies, which undertake to carry out all the pollination work.

To date, the genus Rafflesia includes about 36 taxa, a number of species which, however, are disputed by numerous systematics.

Rafflesia arnoldii, The Largest Flower in the World

The Tetrastigma leucostaphylum Plant is a Major Host of Rafflesia arnoldii
The Tetrastigma leucostaphylum Plant is a Major Host of Rafflesia arnoldii

Origin of Plants

All members of the genus Rafflesia are native to Southeast Asia and in particular:

  • From Thailand
  • From the Malaysian Peninsula
  • From the islands of Sumatra, Java, Borneo and the Philippines

The persistent, well-informed, but also incredibly lucky seeker of their flowers will find them in the tropical rainforest, on level and slightly sloping areas, where plants of the genus Tetrastigma grow. The latter thrive or grow in a variety of soil types, such as:

  • Humic Andosols (Humic Volcanic Soils)
  • Humic Acrisols (Highly Leached Humic Soils)
  • Dystric Fluvisols (Medium Fertility Swampy Flood Soils)
  • Dystric Cambisols (Low Profile & Medium Development Soils)
  • Eutric Fluvisols (High Fertility Swampy Flood Soils)

The Rafflesia arnoldii, on the other hand, originates from the islands of Sumatra and Borneo – only. It is located in virgin, tropical, primary or secondary forests and at an altitude of up to 1000 m.

Rafflesia arnoldii, The Largest Flower in the World

The Rediscovery of the Discovered

It does not matter that the Rafflesia arnoldii flower was spotted by the anonymous Indonesian or Malaysian guide of Joseph Arnold -the first European to look at it- has since been named after the latter.

Nor is it of great value that the controversial financier of the exploration mission, Stamford Raffles, whose name honorably bears the entire genus of Rafflesia plants (which of course were known to the natives), was the one who, expressing his development vision, had said honorably for the Chinese, Indonesians and black Africans, that "The Chinese and natives would be manual labourers, as the negroes are in the West Indies" – since he was a man who looked ahead.

On the contrary, it is of great importance that the Theology of Science should move forward and that the West should reap, with the old and modern colonialism, surplus values that do not belong to it.

Rafflesia arnoldii, The Largest Flower in the World

The Exploration Mission

Key members of the expedition included the Scottish physician and naturalist Dr Joseph Arnold, and the English organizer Sir Stamford Raffles – a British statesman who, among other things, held the position of Lieutenant-Governor of Bencoolen on the island of Sumatra on behalf of British Crown or, to be precise, on behalf of the infamous English, and later British, joint stock East India Company.

With them was the wife of Lieutenant-Governor Lady Sophia Raffles, the local Prince of Manna (Pangeran of Manna) – of present-day city southwest of Sumatra -, as well as some officers from the local ethnicity of the Bugis who formed the guard, and about 40 highly-paid slaves and 60 porters to carry luggage.

The city of Manna was the base of the mission.

The Successful Completion

In the year 1818 CE, and on May 19 or 20, somewhere on the Manna River, the anonymous Indonesian or Malaysian guide – which was mentioned a little above – told Joseph Arnold that he had spotted a huge flower, urging the naturalist to follow him up to there to see it. Joseph Arnold responded: it was indeed an oversized flower, which belonged to the later Rafflesia arnoldii.

The First Impressions of Joseph Arnold by Rafflesia arnoldii

Joseph Arnold’s first impressions of his contact with Rafflesia arnoldii are reflected in the letter he sent to his friend Dawson Turner:

"I had ventured some way from the party, picking specimens of plants, when one of the Malay servants came running to me with wonderment in his eyes, and said, … “Come with me, Sir, come, a flower very large, beautiful, wonderful”. I immediately went with the man about an hundred yards in the Jungle, and he pointed to a flower growing close to the ground under the bushes, which was truly astonishing."

But being amazing does not necessarily mean that it is fragrant:

"When I first saw it a swarm of flies were hovering over the mouth of the nectary, and apparently laying their eggs in the substance of it, it had precisely the smell of tainted beef."

… And because sometimes size matters:

"It measured a full yard across; the petals (which were sub-rotund) being twelve inches from the base to the apex, and it being about a foot from the insertion of the one petal to the opposite one."

Rafflesia arnoldii, The Largest Flower in the World

Flower Buds and a Flower of Stinking Corpse Lily
Flower Buds and a Flower of Stinking Corpse Lily

Botanical Description of Rafflesia arnoldii

Despite the difficulty of studying Rafflesia arnoldii, due to the fragility of the flower and the inability of the plant to reproduce in laboratory or field conditions, a relatively small number of studies, mainly in relation to its impressive and paradox flower, yielded a satisfactory picture of the parasite.

Speaking of paradox, it could be said here that such is not only the flower but also its invisible part, which are filamentous tissues, and not stems, shoots, leaves or roots. The consequence of the above, and without a trace of exaggeration, is that R. arnoldii is recruited and recognized as a plant as soon as its flowering bud appears on the host’s bark.

The Flower

The emerging flowering bud of R. arnoldii going through various developmental stages, eventually appears as a unisexual flower, ie either female or male.

The shape of the flower is corona-like, where around the central structure that looks like a dome – which has a large opening at the top – develop five leathery and hard petals. The petals are reddish brown and are dotted with white spots.

The top of the flower axis, inside the dome, forms a disk, on which emerge numerous thorny organs of unknown function – the so-called "Processes". Below the disc are the male or female reproductive organs of the plant.

The diameter of the flower varies between 90 and 100 to 150 cm, while its weight usually ranges between 9 and 12 kg.

Fragrance

It is a certainty that the large or giant flower of Rafflesia plants is related to the smallest carrion flies in more than one way.

The most obvious from them is through the -let’s say- fragrance or aroma: the attraction of these Diptera takes place by the release of volatile compounds whose diffused "aroma" smells imitating the odor emitted by decayed, rotten flesh.

Indeed, the chemical composition of the compounds contained in the "aroma" largely matches the chemical composition of the compounds responsible for the decaying carcass stench.

Pollination

The pollination of the plants of the genus Rafflesia is carried out – as it was said above – with the carrion flies. For R. arnoldii in particular, this most important biological process is performed exclusively by flies of the genera Lucilia and Sarcophaga – and in particular mainly by females. Insects are tireless air-runners as they can travel up to about 22 kilometers, visiting the flowers.

The corps-like cocktail of volatile substances emitted by plants – the greatest intensity of which is observed on the third or fourth day of flowering – attracts flies. Once they reach the inside of the male flower, they will persistently look for nectar but will not find it. On the contrary, what they will find is what they are not looking for: a huge amount of viscous liquid, the pollen, which will stick to their dorsal, to dry later. Then, visiting the female flowers will complete the pollination process, without having received any consideration, any substantial reward.

However, without the slightest fault of the flies, the pollination of Rafflesia plants is rare, and various factors contribute to this, among which can be included:

  • The high mortality of flowering buds, which reaches a percentage of 80 to 90%, and the consequent reduced flower production
  • The unisexual flowers – the appearance in different plants of male and female flowers
  • The very often great distance between the flowers
  • The many times asymptote of the cofloweringof male and female individuals
  • The short lifespan of plants flower, since each one lives from 5 to 7 days

Biological Cycle

The biological cycle of such a unique parasitic plant as the R. arnoldii, is completed -in general terms- within 3 to 5 years.

More specifically, male flowering plants need about 2 years and 11 months to 4 years and 5 months to complete their biological cycle, while for the same purpose, female flowering plants need about 3 years and 5 months to 5 years and 1 month.

On the other hand, the distinct stages of development of Rafflesia plants are 7, and include:

  • Inoculation of seeds in the host
  • Emergence of the flower bud
  • Mature bud
  • Anthesis
  • Pollination
  • Formation of fruits and seeds
  • Dispersal of seeds

Seed Dispersal & Parasitism

The mode of dispersal of the really huge number of seeds produced from the fruits of R. arnoldii, remains largely unknown. Various hypotheses have been proposed, relating to both animals (such as various species of treeshrews, which are small mammals of the order Scandentia) and insects.

The most prevalent of all seems to be the case of the dispersal of seeds by ants. This is because Rafflesia seeds develop on the pericarp a surrounding tissue called elaiosome.

The elaiosome attracts ants, as it is food for them, and because of this they carry the seeds to their underground nests. There they separate it and eat it or feed their larvae with the elaiosomes, leaving the rest of the seed intact. As a result of all this, the intact seeds may eventually come into contact with the roots of the hosts, when conditions are favorable, infecting them.

When the host is infected, they develop a haustorium and then settle into it. In the host they appear as filamentous tissues that extend between the cells, from which they receive water and nutrients. Especially for water it seems that they have made an excellent choice, since the species in which R. arnoldii parasitizes (ie in one of the Tetrastigma curtisii, T. pedunculare and T. leucostaphylum) are primarily "sources" of water.

This serves the plant unimaginably, whose flowers consist mainly of water, while during the final stages of their development they pump huge amounts of it from their host.

Rafflesia arnoldii, The Largest Flower in the World

Conservation Status of Genus & Species

The genus Rafflesia does not claim to be innovative because its members are in danger of extinction. Various factors contribute to this direction, the common denominator of which is in general – who else? – the well-known Homo economicus.

The latter, by deforesting areas of tropical forests, in sites where the habitats of plants of the genus are located, does what it knows best, that is destroys, and in this case destroys the prospects for the continued existence of these particular parasitic plants.

And although the obvious first answer to this practice would be the absolute protection of Rafflesia’s habitats, this is done spasmodically and fragmentarily, for reasons that we hope will be presented in an upcoming "Kalliergeia" tribute around all of the endangered plant species – to former and post moderns neo-colonies throughout the world.

However, here we must mention that the plants are led to this result unfortunately also due to the scientific weakness, as so far it is not possible:

  • Their ex situ, not natural habitat propagation (despite the successful attempt to produce flowers in the Botanical Gardens of Bogor, Indonesia, but not of their fruiting)
  • Or their in situ, whitin natural habitat conservation, by cultivation methods

For the History we will mention that from all the species of Rafflesia the IUCN (International Union for Conservation of Nature and Natural Resources) has classified:

  • The R. magnifica in the category Critically Endangered (CR)
  • The R. arnoldii in the Vulnerable (VU) category

Rafflesia arnoldii, The Largest Flower in the World

Rafflesia arnoldii (Stinking Corpse Lily) in Full Blooming
Rafflesia arnoldii (Stinking Corpse Lily) in Full Blooming

References

The references of this article with the meaningful title Rafflesia arnoldii, The Largest Flower in the World are presented by the American jazz ensemble Fourplay with their composition Bali Run, from the discographic work that bears their name and was released in 1991.

With Pomp and Circumstance

Fourplay live at the 2011 Java Jazz Festival, perform the Bali Run

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