Rafflesia schadenbergiana is a large flora species endemic to the island of Mindanao, the Philippines. The flower was first collected in 1882 by researchers Alexander Schadenberg and Otto Koch in the forested area of Mount Parag. Its official taxonomic description was later published by botanist Wilhelm Hieronymus.
Following its initial discovery, its existence went unrecorded for over a century. It was even presumed to have gone extinct in the wild. Its presence was only reconfirmed in October 1994 when researcher Pascal Lays discovered a bloom in the Sugud Ebang area, South Cotabato Province.
Anatomical Profile of Rafflesia schadenbergiana
A fully expanded bloom of Rafflesia schadenbergiana measures between 52 and 80 centimeters in diameter. The weight of a single large mature bloom can reach up to 5 kilograms. Its size makes it one of the most massive single-flower structures in Southeast Asia.
Its perigone consists of five thick lobes ranging in color from brownish-orange to deep maroon. Each perigone lobe measures 20 to 23 centimeters in length and 22 to 26 centimeters in width. The outer surface of the lobes is covered with prominent whitish warts that are elongated and irregularly patterned.
The central portion of the flower features a circular disk measuring 12 to 18 centimeters in diameter. The surface of the disk is adorned with 30 to 63 prominent conical processes up to 3 centimeters long. The processes are arranged neatly around the center of the disk in three concentric rings.
Beneath the central disk lies a coarse-textured diaphragm cavity with an aperture diameter of 13 to 15 centimeters. The interior of the perigone tube is lined with branched, hair-like structures (ramenta) measuring 4 to 10 millimeters in length. Male flowers feature 26 to 40 anther sacs deeply immersed within the column sulci.
Parasitic Behavior on Host Plants
The survival of Rafflesia schadenbergiana relies entirely on another plant as an obligate parasite. The plant grows without true leaves, stems, or roots. It depends solely on the vascular tissue of the liana Tetrastigma papillosum to absorb water and nutrients.
Emerging floral buds develop hidden within the root or stem tissue of the host vine. Upon breaking through the surface, the floral bud appears as a dark brown, spherical knob. The bud requires years to mature before blooming. Its flowering period is exceptionally brief, lasting only three to five days before rotting.
At full anthesis, the flower emits a strong, foul odor resembling decaying flesh. The scent serves to attract carrion flies from the families Calliphoridae and Sarcophagidae. Attracted flies crawl into the base of the perigone tube, aiding in the transfer of pollen to female floral structures.
Population Threats in the Wild
In the Philippines, the survival of Rafflesia schadenbergiana faces an extremely high level of threat. The Philippine government has classified Rafflesia schadenbergiana as Critically Endangered on its national red list. At present, its active populations in the wild persist in only a few restricted sites across South Cotabato and Bukidnon.
The primary threat stems from the conversion of lowland rainforests in Mindanao for slash-and-burn agriculture. Land clearing removes canopy trees while destroying the host lianas. Consequently, soil micro-humidity drops sharply, causing flower buds to frequently abort before opening.
References:
- Barcelona, J. F., Pelser, P. B., Balete, D. S., & Co, L. L. (2009). Taxonomy, ecology, and conservation status of Philippine Rafflesia (Rafflesiaceae). Blumea, 54(1–3), 77–93. https://doi.org/10.3767/000651909X474122
- Lays, P. (2006). Rediscovery of a floral jewel in the Philippine archipelago: Rafflesia schadenbergiana Göppert, 1885 (Rafflesiaceae). Lejeunia, 182, 1–10.
