Researchers launch an urgent appeal to save the world’s largest flower, Rafflesia, from extinction

An international group of scientists, including botanists at the University of Oxford Botanic Garden, has issued an urgent call for coordinated action to save the famous Rafflesia genus, which has the largest flowers in the world. It follows a new study that found most of the 42 species are critically threatened, yet only one of them is listed on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Furthermore, more than two-thirds (67%) of plant habitats are unprotected and at risk of destruction.

The work is published in Plants, people, planet.

Rafflesia, one of the greatest botanical mysteries, has aroused the curiosity of scientists for centuries. The plant is a parasite that infects tropical vines in forests across Southeast Asia (Brunei, Indonesia, Malaysia, Philippines and Thailand). For most of its life cycle, Rafflesia is hidden from view, existing as a system of thread-like threads that invade its host. At unpredictable intervals, the parasite produces a cabbage-like bud that penetrates the bark of the vine and eventually forms a giant five-lobed flower up to a meter across. This produces a foul odor of rotting flesh to attract pollinating flies, earning it the alternative name “corpse flower.”

With such an elusive life cycle, Rafflesia is still poorly understood, and new species are still being recorded. In order to better understand the vulnerability of these unique plants, a group of scientists has established the first coordinated global network to assess the threats facing Rafflesia.

The results of the study found that all 42 Rafflesia species are threatened with extinction. Based on criteria used by the International Union for Conservation of Nature, scientists have classified 25 species as “critically endangered,” 15 as “vulnerable,” and two as “vulnerable.” Furthermore, more than two-thirds (67%) are not protected by regional or national conservation strategies.

The distribution of Rafflesia species is often very limited, making them particularly vulnerable to destruction of their natural habitat. The study found that many remaining populations contain only a few individuals located in unprotected areas and at risk of conversion to agriculture. Because attempts to propagate Rafflesia in botanical gardens have had limited success so far, this makes habitat conservation an urgent priority.

To address these threats, researchers recommend that all Rafflesia species be immediately added to the IUCN Red List of Threatened Species. Currently only one is listed: Rafflesia magnifica.

The team proposes a four-point action plan for governments, research centers and conservation organizations:

• Greater protection of Rafflesia habitats, targeting the most vulnerable populations. Habitat protection has been identified as the best tool for Rafflesia conservation. Southeast Asia has the fastest disappearing forests on the planet, and many of the best-known Rafflesia populations are dangerously close to growing human settlements.

• A better understanding of the full diversity of Rafflesia that exists, to guide decision-making. It is believed that Rafflesia species remain undocumented, while others became extinct before science even knew them. We cannot protect what we do not know exists, so sampling campaigns and genetic analyzes are needed to understand how many species of Rafflesia actually exist.

• Develop methods for successfully propagating Rafflesia beyond its native habitat. This can include grafting Rafflesia-infected vines onto uninfected vines of the species whose habitat is likely to be destroyed.

• Introducing new ecotourism initiatives to engage local communities in the conservation of Rafflesia. Providing funding and training for local specialist guides would be an effective way to help protect the local Rafflesia population and raise awareness of the need for environmental conservation.

Despite the challenges, the study also highlighted valuable success stories that could provide important insights for Rafflesia conservation elsewhere. For example:

• The Bogor Botanical Garden in West Java, Indonesia, has become a center of excellence in Rafflesia propagation, after a series of successful flowering events, including 16 events for Rafflesia batma. Knowledge exchange activities will help disseminate best practices in areas that urgently need them.

• In West Sumatra, groups of local villagers are taking advantage of ecotourism in Rafflesia by forming “bukdarwis”: social media-linked tourism outreach groups. Many of these advertise Rafflesia boom events on social media platforms to build population awareness, attract paying tourists while carefully managing risks of, for example, trampling. These activities can be developed as a model for dissemination in areas where community participation in Rafflesia conservation is rare.

Dr Chris Thorogood, Deputy Director of Oxford University Botanic Gardens and author of the study, said: “This new study highlights how global plant-oriented conservation efforts – however distinctive – have lagged behind those of animals. We urgently need a joint, cross-regional approach to saving animals. “Some of the world’s most magnificent flowers, most of which are now on the verge of being lost.”

Adrian Tobias, a forester from the Philippines, added, “Indigenous peoples are some of the best custodians of our forests, and Rafflesia conservation programs are more likely to succeed if they involve local communities. Rafflesia has the potential to become a new symbol of our forests. Conservation in the Asian Tropics.”