Rafflesia
(Rafflesia genus)

Description
Rafflesia has the largest flower in the world. It is a rainforest plant which parasitises Terastigma vines, producing a massive single flower of five leathery orange petals, which can be up to 1 m in diameter.

Distribution
Found in the rain forests of south-east Asia; Borneo, Sumatra, Thailand and the Philippines.

Biology and development
There are 13 species of Rafflesia. It lives by parasitising a host vine and absorbing nutrients through a mesh of single-celled filaments, similar to those of some fungi. There are no leaves, roots or stems. Only the foul smelling, insect pollinated flowers are obvious, and these are produced after 5 years of parasitic growth within the host vine.

Initially, where the vine lies slumped on the ground and thinly covered by soil, several buds appear. However, many rot or are damaged by animals before they open. When the flower does at last open, it has five red, cream-spotted petals surrounding a larger bowl containing the sexual parts of the flower. Male and female flowers occur on separate plants - the latter are more rare.

The smell emitted from the plant attracts flies who crawl towards the central disc of reproductive organs. Thick hairs and translucent windows in the flower structure guide the insects, which act as pollinators. Within four to five days the flower will completely rot.

Reasons for decline
Logging activity has greatly reduced the available habitat for the host vine. The large size of the flower has also led to souvenir hunters, and local peoples have used the flowers for medicinal purposes. Of the 13 Rafflesia species, two have not been seen since the Second World War and are presumed extinct. Cultivation of the plant has not, so far, been possible.

Current status
No population estimates are available. The life of the plant includes a largely non-visible stage within the host vine and flowering cannot be predicted.

In Sabah, in northern Borneo, a local project to locate and preserve selected sites has been set up. Wood cutting is limited in these areas and all sightings of Rafflesia are reported to the local university.

Being a total parasite, it is entirely dependant on its host plant. This overspecialisation may also lead to its eventual elimination, for as the host plant is lost to habitat destruction, so is the Rafflesia.

References
Attenborough, D. (1995) The Private Life of Plants. BBC Books.

Rafflesia (Rafflesia genus)

kingdom:		Plantae
phylum:		Angiospermae
class:		Dicotyledoneae
order:		Aristolochiales
family:		Rafflesiaceae
genus:		Rafflesia

size:		1 metres
mass:		Up to 11 kilograms