World’s largest flowers are facing extinction

Most plants in the Rafflesia genus – which have the largest known flowers in the world – are under threat of extinction, according to an international team of botanists.

Native to Southeast Asia, Rafflesia plants have life cycles so bizarre that botanic gardens like the UK’s Royal Botanic Gardens at Kew, struggle to cultivate them.

The plants spend most of their time as invasive thread-like filaments, parasitising jungle vines. Then, when it’s time to pollinate, they burst out of vine bark in massive flowers, up to a metre in size.

The flowers reek of rotting flesh, to attract flies. This has also earned Rafflesia the nickname “corpse flower” (not to be confused with Sumatran Titan Arum, which are also called corpse flowers but are an entirely different species).

Giant flower in jungle
Rafflesia bengkuluensis, Sumatra. Credit: Chris Thorogood.

It’s very difficult to predict when a flowering will happen – and this combined with the rest of the mysterious life cycle has made Rafflesia plants very hard to cultivate.

There’s also little known about how many species there are in total. Scientists have recorded 42 different Rafflesia species across Brunei, Indonesia, Malaysia, the Philippines, and Thailand – some of them just from a single bud. New species are still being found, and the current categories are changing as scientists learn more.

Person in jungle with giant flower
Chris Thorogood with Rafflesia arnoldii, the largest flower in the world, in Sumatra. Credit: Chris Thorogood.

Because of all of this mystery, just one Rafflesia species (Rafflesia magnifica) is listed as endangered on the International Union for Conservation of Nature and Natural Resources’ (IUCN) Red List. A paper in Plants People Planet says that number should be much higher.

The researchers estimate that 60% of Rafflesia species face a “severe risk of extinction”, making them Critically Endangered by the IUCN’s standards, and they find that at least 67% of known habitats aren’t protected areas.

Inside of flower
A rare glimpse into the interior of Rafflesia arnoldii. Credit: Chris Thorogood.

“A combined approach might just save some of the world’s most remarkable flowers, most of which are now on the brink of being lost,” write the researchers in their paper.

The researchers have proposed a four-pronged approach to saving Rafflesia:

  • Protecting habitats – this was considered the single best tool for saving the genus.
  • More research for a better understanding of Rafflesia.
  • Finding out how to propagate Rafflesia outside their native habitat – at the moment, this is still very difficult, although Bogor Botanic Garden, near Jakarta in Indonesia, has had some success.
  • Ecotourism initiatives to engage and incentivise local communities: this has had success in West Sumatra.

“Indigenous peoples are some of the best guardians of our forests, and Rafflesia conservation programmes are far more likely to be successful if they engage local communities,” says paper co-author Adriane Tobias, a forester from the Philippines.

Rafflesia has the potential to be a new icon for conservation in the Asian tropics.”

Group of people around giant flower
Rafflesia bengkuluensis with its custodians in Sumatra. Credit: Chris Thorogood.

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