Rafflesia is one of the largest flowering plants in the world, with a flower diameter of 10-150 cm. Its size varies depending on the species. Besides its large size, Rafflesia is also characterized by a foul odor emitted during blooming, often referred to as the "corpse flower."
In Indonesia, there are two plants referred to as corpse flowers, namely Rafflesia and Amorphophallus. These are sometimes confused due to the common name, but they are different species. Rafflesia is a single flower from the Rafflesiaceae family, while Amorphophallus is a compound flower from the Araceae family, commonly known as the elephant yam.
Interestingly, despite its large size, Rafflesia is an obligate parasite, relying entirely on its host plant, Tetrastigma, for its life requirements. Another unique feature is that it only exists as a flower, lacking leaves, stems, and roots. Its presence is only noticeable when a knob emerges on the stem or roots of Tetrastigma, which later grows into a blooming flower.
There are three developmental stages of the knob in the Tetrastigma stem/roots before blooming: copula, bract, and perigone. Copula is the small knob of Rafflesia still covered by the skin of the Tetrastigma stem/roots. Bract is an individual Rafflesia that is a larger knob, resembling a cabbage, covered by several layers of black sepals. Perigone is the Rafflesia individual in the pre-blooming stage, a large reddish knob with a diameter of over 10 cm, the upper part of which is no longer covered by black sepals.
Unlike other spermatophytes, different parts of the Rafflesia flower are referred to by specific terms: perigone, diaphragm process, disc, ramenta, and annulus. The flower size and these parts serve as the basis for distinguishing Rafflesia species. Perigone is the floral crown usually red or orange, adorned with dots of varying patterns, depending on the species. The diaphragm surrounds the opening to the perigone tube. Ramenta are hairs growing inside the perigone tube, having different shapes and sizes in each species. The disc is a plate in the middle of the perigone tube, containing a pointed cone-shaped organ called the processus. Below the disc, at the base of the perigone tube, there is an annulus, a circular arch surrounding the base of the perigone tube, with a variable number, 1-2, depending on the species. In male flowers, anthers are stored beneath the disc plate, while in female flowers, stigmas are located behind the disc, connected to the developing fruit at the base of the perigone tube.
Rafflesia is reported to grow only in the Southeast Asia region, in five countries: Thailand, Malaysia, Indonesia, Brunei Darussalam, and the Philippines. In Indonesia, Rafflesia is reported to grow on three major islands (Sumatra, Java, and Kalimantan) and surrounding smaller islands, such as Nusa Kambangan and Mursala.
Various Rafflesia species in Indonesia are protected by the Ministry of Environment and Forestry Regulations No. P.106/MENLHK/SETJEN/KUM.1/12/2018 and No. P.71/ /MENLHK/SETJEN/2015 regarding the Rafflesiaceae Conservation Action Plan Strategy for 2015-2025. However, the Rafflesia population in Indonesia is believed to be declining and facing the threat of extinction (Thorogood et al. 2023).
Several factors contribute to the extinction of Rafflesia in Indonesia, including biological, ecological, catastrophic, and anthropogenic factors. Biologically, the success of knobs reaching the blooming stage is low, with a high mortality rate, and the exact causes are unknown. Moreover, the proportion of male flowers is greater than that of female flowers, and the simultaneous blooming of male and female flowers is rare, reducing the chances of natural reproduction.
Ecologically, the obligate parasitic nature of Rafflesia on Tetrastigma and the growth of Tetrastigma affected by the presence of structural hosts make Rafflesia vulnerable. Deforestation rates in Indonesia contribute to the extinction of Rafflesia, as disruption to Tetrastigma and its structural hosts can lead to Rafflesia's demise. Additionally, certain animals are reported to prefer Rafflesia, and predation contributes to death and hinders the reproductive process.
Natural disasters also contribute to Rafflesia extinction. The 1994 tsunami in southern Banyuwangi led to the disappearance of a portion of the R. zollingeriana population in Meru Betiri National Park. The last factor is human activity, particularly the illegal collection of Rafflesia flowers for excessive and unrestricted medicinal purposes.
In the IUCN Red List of Threatened Species 2023, only one Rafflesia species, Rafflesia magnifica, found in the Philippines, is known to have a conservation status: critically endangered. Other species, especially those in Indonesia, have not been assessed or updated.
Rafflesia research in Indonesia progresses relatively slowly compared to other countries. In the last 20 years, taxonomy studies in Indonesia have only identified four new species. This achievement lags behind Malaysia and the Philippines, which have described seven and eleven new species, respectively. Research on Rafflesia in Indonesia is primarily focused on ecology, with minimal exploration of its biology. However, biological information is crucial for understanding and formulating conservation efforts, both in-situ and ex-situ.
Information about new Rafflesia habitats in Indonesia is available, especially online and through social media (citizen scientists). However, this does not necessarily lead to the discovery of new species, as most reported Rafflesia habitats are in remote, inaccessible locations or require significant funding to reach. The technical difficulties of accessing these remote locations hinder regular observations necessary to answer many of the significant biological questions about Rafflesia.
The sluggish pace of Rafflesia research in Indonesia is concerning, given the high deforestation rates in Indonesian forests. The Rafflesia population is at risk of disappearing before it can be thoroughly studied. Collaboration among various stakeholders is needed to address this issue. Firstly, Rafflesia must be conserved both ex-situ and in-situ. Easily accessible ex-situ habitats for Rafflesia are essential, particularly for further studies and public education.
In recent years, successful propagation of Rafflesia ex-situ has been achieved through root grafting and seed inoculation at the Bogor Botanical Gardens, with the successful growth of Rafflesia patma. The success of ex-situ conservation methods should be communicated to relevant stakeholders, especially to in-situ area managers and local communities, to be implemented in natural habitats, especially for species that cannot be conserved ex-situ. In-situ propagation should be carried out in representative but easily accessible in-situ areas, facilitating further research and ecotourism. Research in these in-situ habitats should collaborate with local flora enthusiast communities and nearby research institutions, such as local universities. The participation of local communities and universities is expected to gradually fill the scientific information gap about Rafflesia.
Currently, the potential sustainable utilization of Rafflesia is seen in ecotourism. This initiative has begun in various regions of Indonesia, particularly on the island of Sumatra. However, the recommended approach for Rafflesia ecotourism is guided ecotourism, involving local communities as operators. Guided ecotourism for Rafflesia needs to be conducted in a controlled manner to prevent damage to existing populations, given that the presence of Rafflesia knobs is not easily noticed by those unfamiliar with them. Involving local communities in ecotourism activities is crucial to enhance their motivation in conserving both Rafflesia and the overall natural habitat. Zuhud (2008) stated that economic incentives are more effective in increasing community participation in conservation efforts.
Hopefully, with these efforts, the Rafflesia population in Indonesia can continue to thrive for the benefit of both basic and advanced research. Research endeavors should explore its potential, allowing the existence of Rafflesia to be utilized more widely by future generations.
This article is a translation of an article compiled by the author (Dewi Lestari) and published on Kumparan in Indonesian
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