The World’s Largest Flower (Borneo #2)

Rafflesia flowers are among the great natural history treasures of Borneo. There are some 16 species with one species, R. arnoldii, spanning 97 cm in diameter. They and one other genus are in their own family, the Rafflesiaceae. You can imagine the sensation the flower caused when it first appeared in Europe in 1820.

The genus is named in honour of Sir Stamford Raffles by Joseph Arnold who was working for Raffles company when he made the discovery in Sumatra. Tragically Arnold died of Malaria on the homeward trip and did not live to receive the accolades of his discovery. Rafflesia also occurs in Java, Thailand, Philippines and Peninsular Malaysia.


DR near Poring Hot spings on the slopes of Mt Kinabalu, Sabah, Borneo. R. keithii A. Lamat photo.


Rafflesia keithii has 5 petal-like lobes surrounding the central opening. Male and female flowers look similar but have the appropriate sexual organs within. The central "nectarium" can contain " 15 pints of liquid and the flower may weigh 15 pounds". A. Lamat photo


The brown, soft-ball sized bud of R. keithii emerges and takes several months to open. But once opened, the flower lasts only a few days. A. Lamat photo


More advanced bud of R. keithii. A. Lamat photo

Rafflesias are not really flowers in the traditional sense. I was fortunate enough to be able to see living plants on the lower slopes of Mt Kinabalu in a small portion of forest. The plants are parasites of the Tetrastigma vine (a member of the grape family with species in Australia) and cannot grow on their own. They have no leaves and the tiny roots emerge from the host plant without causing any substantial destruction. The flower itself is a complex structure unlike any other in the plant kingdom. There are male and female flowers but you have to look closely to spot the differences. The spike-like “processes” of the centre of the plant seem to distribute heat and help intensify the odour of rotting meat that the flowers produce. This attracts calliphorid flies of the genera Chrysomyia and Lucilia that serve as pollinators. The white spots seem to guide the flies back outside once they have received the pollen. Not all Rafflesia species have these spots. The biology of Rafflesia requires that male and female plants flower at the same time in proximity. The developing seeds are thought to be distributed by squirrels, pigs and tree shrews. Insects such as termites and ants may also play a role.

Well if Rafflesia is not a true flower, what is the world’s largest flower? This accolade probably goes to members of the Araceae, the “Man and ladies” family which includes Philodendron and Anthurium as popular examples. The Titan Arum, Amorphophallus titanum, is probably the world’s largest flower with one specimen recorded as reaching 5 feet 8 ½ inches in height. It is from Sumatra.




A beautifully written and illustrated book has been written on the Rafflesias of Sabah. It is published by the Borneo Publishing Company.


A postcard with 4 species of Borneo Rafflesia. Left to right R. tengku adlinii; R. pricei; R. keithii; R. tuanmudae.