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Home » World’s Largest Flowers at Risk of Extinction, Scientists Warn

World’s Largest Flowers at Risk of Extinction, Scientists Warn

The iconic giant Rafflesia flowers are disappearing at an alarming rate, according to new research published in Plants, People, Planet.

An international team of scientists conducted the first comprehensive assessment of extinction risk for all known Rafflesia species. Their findings reveal that over 60% of the 42 known species face a severe threat of extinction. Rafflesia produce the world’s largest individual flowers, which can grow over 3 feet wide. However, most species have highly restricted ranges in Southeast Asia’s rapidly vanishing rainforests.

A blood red plant squats by the base of a tree in a dark rain forest. Its petals are marked by white sickly spots that make it look like it should smell repulsive. This is a flower you'd bring to the funeral of someone you really disliked.
Rafflesia banaoana. Credit Chris Thorogood

The study, by Pastor Malabrigo Jr. and colleagues, estimated that 25 Rafflesia species qualify as Critically Endangered based on small geographic range size and limited number of locations. The researchers also found that at least 67% of known habitats are outside of protected areas, making the plants even more vulnerable.

Rafflesia are unusual rootless parasitic plants that live inside vines of the genus Tetrastigma. This lifestyle makes them extremely difficult to propagate or transplant. Most species are only known from a single locality and have tiny populations.

Deforestation is the primary threat, as logging and land conversion for agriculture have destroyed vast areas of Southeast Asia’s tropical rainforests. Rafflesia species literally live on the edge – often in small forest fragments. Alarmingly, the paper documents probable extinctions of Rafflesia even before the plants were formally described by science. Malabrigo Jr. and colleagues write:

In situ conservation in Indonesia is challenging and interdependent on multiple variables, including economic growth, increasing pressure on habitats linked to land use, and a poor understanding of the ecology and distribution of most species; it is impossible to conserve populations not known to exist. Less-explored Kalimantan is likely to host poorly known species of uncertain taxonomic status. For example, three unassigned taxa were documented on Mount Sekerat in northeast Kalimantan (Meijer, 1997). Recently, a team from the Indonesian National Research and Innovation Agency (BRIN) examined the area and found no extant Rafflesia populations; they appear to have been lost to land conversion. Hitherto unreported, this is a highly concerning example whereby three species may have been lost before they were even known to science. 

Malabrigo Jr et al. (2023)
A young gentleman attempts to look pleased that he's holding up the largest flower in the world. His posture indicates pride in his achievement, but the look on his face indicates he's like the photo taken quickly due to the smell.
Chris Thorogood with Rafflesia arnoldii, the largest flower in the world, in Sumatra. Credit Chris Thorogood

Dr Chris Thorogood, Deputy Director of the University of Oxford Botanic Garden and an author of the study, said: ‘This new study highlights how the global conservation efforts geared towards plants – however iconic – have lagged behind those of animals. We urgently need a joined-up, cross-regional approach to save some of the world’s most remarkable flowers, most of which are now on the brink of being lost.’

Yet, the assessment is not all negative. According to the study, community-led conservation initiatives have successfully protected some Rafflesia habitats, especially when they are sources of ecotourism revenue.

Adriane Tobias, a forester from the Philippines, said: ‘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. Rafflesia has the potential to be a new icon for conservation in the Asian tropics.’

A Rafflesia flower that looks like it's been put through a washing machine, and the dye from its petals has run out, leaving a pastel orange flower.
Rafflesia bengkuluensis, Sumatra. Credit Chris Thorogood

To prevent further losses, the researchers recommend strengthening taxonomy, expanding protected areas, propagating species ex-situ, and supporting community engagement. With Rafflesia facing existential threats across their range, the study argues that a multi-pronged approach is urgently needed to save these ecological wonders.

Malabrigo, P., Jr, Tobias, A.B., Witono, J., Mursidawati, S., Susatya, A., Siti-Munirah, M.Y., Wicaksono, A., Raihandhany, R., Edwards, S. and Thorogood, C.J. (2023) “Most of the world’s largest flowers (genus Rafflesia) are now on the brink of extinction,” Plants, People, Planet. Available at: https://doi.org/10.1002/ppp3.10431.

Cover: Rafflesia kemumu in the rainforest of Sumatra. Image: Chris Thorogood.

Alun Salt

Alun (he/him) is the Producer for Botany One. It's his job to keep the server running. He's not a botanist, but started running into them on a regular basis while working on writing modules for an Interdisciplinary Science course and, later, helping teach mathematics to Biologists. His degrees are in archaeology and ancient history.

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