There are 17 kinds of rafflesia.
They grow in tropical forests.
The flower of Rafflesia arnoldi is the largest flower in the world.
It can be one metre across!
Seventeen species (kind)
There are over 17 species, or kinds, of rafflesia, all bearing huge blooms, but one of them, with the scientific name of Rafflesia arnoldii, bears the largest flower in the world, measuring about 1 metre across and weighing up to 10 kg.
The rafflesia was named after Sir Thomas Stamford Raffles who, in 1818, led an expedition into the rainforest that led to its discovery.
Where it grows
The rafflesia species grow in the warm and humid, lowland Southeast Asian rainforests of Malaysia, the Indonesian islands of Sumatra and Java, southern Thailand, Borneo and the southern Philippines.
Rafflesia arnoldii is found only in Borneo and on the Indonesian island of Sumatra.
Growing on another plant
Rafflesia is a group of plants that do not convert sunlight into energy like other plants, has no roots or leaves, and is in fact a parasite. This means it grows on another plant, which is called the host plant, and takes nutrition from it. Rafflesia is a parasite on only one plant, the tetra stigma vine, a member of the grape family that lives only in rainforests.
The main part of rafflesia is invisible most of the time, hidden inside the woody stem of its host. On occasion, a rafflesia bud emerges through the bark of the host, and slowly, over a few months, develops into a huge flower that is either male or female. There are five large, fleshy petals attached to a large cup. In the centre of the cup there is a column with a disk, underneath which are the male (anthers) or female (styles) parts of the plant. The fruits are berries with tiny seeds.
A dreadful smell!
As if the sheer size of the flower is not enough, it has a strong and most dreadful smell of rotting flesh, which gives rafflesia the local name of ‘corpse flower’. However, this smell is irresistible to carrion-flies which crawl all over the flower. In doing so, pollen sticks to the backs of the flies. The plant’s survival depends on flies who visit a male flower first and then fly away to find a female rafflesia, where they will deposit the pollen. The rafflesia flower lasts only 5 or 6 days.
They are rare
Rafflesia species are rare for several reasons.
- They have what is known as a double specialisation: they can only grow on one species of vine, which in turn is only found in very specific habitats.
- Only about 20% of buds survive to bloom.
- There seem to be more male flowers than female, and they bloom for a very short time, which makes the chances very small of a male and female blooming at the same time close enough together to be pollinated.
- In addition to these natural threats, Southeast Asian rainforests are being destroyed at a great rate, and rafflesia buds are also harvested for use in traditional medicine, although scientific research has proven that this belief is not based on fact.
Habitat protection is one of the keys to the survival of these plants.
Rafflesia species are protected in a number of reserves.
On the IUCN Red List of Threatened Species:
Rafflesia magnifica is classified as Critically Endangered;
Rafflesia manillana is classified as Endangered;
Rafflesia keithii and Rafflesia pricei are classified as Vulnerable;
Rafflesia cantleyi, Rafflesia kerrii and Rafflesia zollingeriana are classified as Rare.
Rafflesia arnoldii has not been assessed by the IUCNRed List, but is considered to be vulnerable because of disturbance of the forests by tour groups hoping to see it. However this interest is an incentive to local people to preserve the plant because it brings tourism money to the economy.