Hallowe’en and the Monster Plant

This week, the biggest flower on the planet, also known as the “Queen of all Parasitic Plants”, has come to Oxford - but not in the way you would might expect.

Rafflesia arnoldii, famous for producing the largest individual flower known on earth, is one of the most unusual and fascinating botanical phenomena. Native to southeast Asia, the flower can grow up to 1.5 metres across and weigh up to 10kg. This rare and highly unusual plant has no chlorophyll and does not undergo photosynthesis. It is an endophytic holoparasite, obtaining all its water and nutrients from host cells of vines in the Testrastigma genus.

The plant has blossomed at Oxford Botanic Garden in the form of a ‘3D oil painting’, made from papier-mache, plaster, clay and oil paint. It is on display for eight days, representing the length of time the flower blooms in its natural habitat. The man behind the replica, Dr Chris Thorogood, agreed to meet to share his story and reveal the purpose of his life-like representation of this mysterious flower.

Dr Chris Thorogood and his 3D oil-painting of Rafflesia arnoldii.
Dr Chris Thorogood and his 3D oil-painting of Rafflesia arnoldii.

Chris is the Head of Science and Public Engagement at the Oxford Botanic Garden. His work focuses on creating a public interest and awareness in the field of Botany, whilst also conducting research into areas such as evolutionary biology and genetics. Chris expressed his belief that public engagement comes in a variety of forms, some of which he uses, such as Instagram, blogs and Facebook live videos, to spread his passion for Botany.

His model is a beautiful representation of the real flower – but does not smell anywhere near as bad! When in bloom, Rafflesia arnoldii is pollinated by carrion flies, and attracts these flies by producing volatile compounds, chemically similar to those emitted by rotting meat. This method of releasing an odour of decaying meat means that the flower does not need to produce sugary nectar, an energetically expensive process. Rafflesia arnoldii’s method of pollination could explain its size since, as Chris explained: “Flies may respond to a larger flower that can emit more of its smell, whilst also being attracted to what they think is a larger corpse, as it would be a larger resource to lay their eggs and for the maggots to grow on.”

Rafflesia arnoldii has never been grown out of its natural habitat, and the ambition behind the 3D model was to “bring to life something that very few people get the opportunity to see”. Chris first saw the flower in 2005, when exploring the rainforests of Mount Kinabalu, Northern Borneo, in a search for pitcher plants. The mountain is well-known for its remarkable diversity of orchids and pitcher plants. At the bottom of the mountain there are areas of rainforest, in which two species of Rafflesia, namely Rafflesia pricei and Rafflesia keithii, are native. He explained that seeing the flower was “something you don’t forget” and this inspired him to create his 3D replica, in order to share his first-hand experience.

When asked about the benefits of creating a model over paintings or photographs, he said: “It’s a conversation piece, because it’s a model and not the real thing, and that’s generating lots of interest. It’s engaged with the public and with people we wouldn’t usually engage. It really brings the scale, and the whole thing, to life, in a way we can’t yet do.”

Horticultural and logistical challenges, so far, have prevented the flower from being grown in the Western world. In the wild, 90% of Rafflesia buds die as they’re developing, most likely due to rejection from the host plant. Chris explained: “Even if you were successful in getting it to the bud stage, the chances of it actually flowering are very slim”. With an array of challenges and limited knowledge on how to cultivate the flower, it remains as a botanical obscurity. However, Chris was optimistic that it is “not impossible”, and that the great thing for the Oxford Botanic Garden was that, by displaying his replica, it showed their focus and intention of growing the largest flower in the world some time in the future.

If you want to catch it though, you’ll have to be fast. This monstrous vampire will be gone from Oxford Botanic Garden after Hallowe’en.