The Rafflesia, the world’s largest flower,
is a parasitic plant found only in Southeast Asia,
and then only in sub-montane hilly forests at elevations
between 400-1,300 metres. Sir Stamford Raffles and
Dr Joseph Arnold were the first Europeans to discover
the Rafflesia. In 1818, whilst on a field trip near
the town of Bencoolen (Bengkulu) in Sumatra, they
came across a huge specimen that measured 97 cm in
diameter. This species was later named the Rafflesia
Arnoldi. When news of the discovery reached the botanical
community in 1820 it caused quite a sensation with
murmurings of disbelief.
There are thought to be 17 species of Rafflesia,
some of which may already be extinct. Three species
are found in Sarawak - the Rafflesia
Pricei, Rafflesia Arnoldi and Rafflesia Tuan-Mudae, which is actually
a type of Arnoldi. Only one species, R. Tuan-Mudae,
is found at Gunung Gading.
The Rafflesia is as unusual as it is spectacular.
Much of the flower’s biology remains a mystery
to this day. It has no specific flowering season
and it has no roots, leaves or stem. The Rafflesia
depends on a host vine - the tetrastigma, a member
of the grape family. Scientists are still unsure
why the Rafflesia associates itself with the tetrastigma vine or how the seeds of a Rafflesia germinate and
grow. What is known is that threads of tissue spread
out within the vine and absorb nutrients. After 18
months a small dark brown bud appears.
Such a long period of growth means that there is
a high risk of damage; even when a bud forms there
is no guarantee that it will mature into a Rafflesia
flower. A bud takes nine months to mature, when it
may measure up to 16 cm in diameter, and studies
have shown that a high percentage of buds do not
survive, as they are susceptible to both drought
and heavy rain.
After nine months the brown ‘leaves’ of
the cabbage-like bud open, revealing the underside
of the petal-like lobes. It takes several hours for
a flower to open fully. There are usually five thick
and fleshy red-coloured petals, covered in lighter
coloured spots, warts and blotches. The Rafflesia
only blooms for 3-5 days, before it starts to blacken
and rot. Although it is quite common for a number
of buds to occur in a cluster at the same site, it
is rare for two plants of the same cluster to bloom
at the same time.
Rafflesia flowers are either male or female, and
therefore cannot self-pollinate. For pollination
to take place, a male and a female flower must bloom
at the same time and pollen must be transported over
considerable distances. In the Rafflesia’s
case pollination is carried out by carrion flies,
so whilst in full bloom the Rafflesia gives off a
foul smell of decaying flesh to attract them. Seeds
are thought to be dispersed by rodents and other
small mammals which eat the flowers. Scientists remain
baffled, however, as to how the tiny seeds infest
the roots and stems of the host vine.
Loss of habitat is the greatest threat to the survival
of the Rafflesia. Its reliance on the tetrastigma vine does not help matters. With other endangered
species it is possible to implement a range of conservation
measures such as trans-location and the establishment
of nurseries. However, these measures are not possible
with the Rafflesia due to its very high degree of
specialisation. The establishment of totally protected
conservation zones is the only way to preserve this
unique plant.
Gunung Gading National Park in Southwest Sarawak
is such a conservation zone. Gazetted in 1983, the
park covers an area of 4,106 hectares and forms a
safe and secure habitat for the protection of the
Rafflesia.
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