A striking discovery has emerged in plant science. Scientists from the Royal Botanic Gardens have identified the only known member of the palm family that develops and bears fruit almost entirely underground. This distinctive palm has been named underground pinanga.
Native to the tropical island of Borneo in Southeast Asia, the plant is familiar to locals who enjoy its bright red fruit, a sweet, juicy delicacy eaten across parts of the island. The research team has described about 300 palm species on this large island, with underground pinanga standing out for its unusual growth pattern.
Underground pinanga is part of the more than 2,500 palm species known to science, with many facing the threat of extinction. The new palm is found scattered through the primary rainforests of western Borneo, crossing regional borders from Sarawak in Malaysia to Kalimantan in Indonesia. Before its formal description, the plant was known in at least three Borne languages under names such as Pinang Tanah, Pinang Pipit, Muring Pelandok, and Tudong Pelandok.
hidden in sight
Although the plant and its fruit are well known to Indigenous communities on Borneo, it had eluded the scientific community. Underground pinanga surprised the researchers, who used this moment to stress the importance of closer collaboration with Indigenous knowledge about land and forests.
Researchers were first alerted to the palm’s existence by co author Paul Chai, a Malaysian botanist, who encountered the palm in 1997 while visiting the Lanjak Entimau Wildlife Sanctuary in Sarawak. He observed the fruit exposed among thick leaves. In 2018, Kew scientists Benedikt Kuhnhäuser, Peter Petoe and William Baker revisited the sanctuary and collected several palm specimens for study.
“A once in a lifetime discovery”
Professor Benedikt Kuhnhäuser from RBG Kew commented that without the warning from a Malaysian colleague the team might have mistaken this new species for a common seedling and removed it. The team described a rare case of geobloom, an underground flowering phenomenon, marking the first known instance within the palm family. It represents a genuine once in a lifetime finding.
“We have identified a remarkably rare geobloom, an underground flower”
Independent of the team, Indonesian researcher and lead study author Agusti Randi collected palm specimens in Kalimantan in 2017. Some of these plants were damaged or consumed by wildlife, yet the collaboration of Indonesian, Malaysian, and Kew scientists culminated in naming underground pinanga as a new species for science.
an unusual discovery
Agusti Randi explains that when he first found this dwarf palm in a forest in West Kalimantan in 2017, boars were digging around a population of underground pinanga and several ripe, bright red fruits lay on the ground. Soil around the trunks showed signs of rooting by boars searching for underground fruit, with seeds scattered in their tracks.
At first glance the species resembles a young specimen of other common Borneo rainforest palms. Palm seedlings often blanket the forest floor, making them easy to overlook. In this case, however, seemingly young plants are fully developed adults with reproductive parts hidden below the soil surface.
Despite initial attention from Paul Chai, scientists needed to prove that underground pinanga is indeed a new species. The genus pinanga contains many small upright palms found primarily undercover on the forest floor. More than a hundred species reside in Southeast Asia, with Borneo serving as a center of diversity. To confirm underground pinanga as a distinct species, Agusti Randi meticulously compared specimens with all known Bornean pinanga species and established its novelty.
Flowers and fruits underground
Most flowering plants, known as angiosperms, develop their flowers and fruits above ground to aid pollination and seed dispersal. A small group has evolved to thrive and bear fruit underground, a phenomenon called geoblooming and geocarpy. This pattern has been observed in about 171 species across 89 genera and 33 plant families. For instance, peanuts form above ground, but the fruit develops underground. Fruiting and flowering entirely underground remains exceptionally rare and has been noted in the orchid genus Rhizanthella by researchers, to their knowledge.
This underground behavior surprised scientists because it seems to hinder pollination and seed dispersal. The new species underground pinanga challenges these assumptions and the researchers hope the discovery will attract others to unravel remaining mysteries surrounding this unique plant.
How does pollination occur?
Professor William Baker, Senior Research Leader, Tree of Life at RBG Kew, notes that palm pollination continues to astonish after three decades of study. The underground flowering observed in underground pinanga raises questions about pollinator behavior, how pollinators access concealed flowers, and how this evolutionary path developed for future palm surprises.
In underground pinanga, the combination of geocarpy and geoflora remains perplexing since Pinanga species are typically pollinated by insects like bees, which cannot move underground with ease. Yet a robust seed set is observed, suggesting an efficient underground pollination mechanism that invites further investigation into soil processes and plant biology.
Researchers have already traced how the seeds spread through the tropical forest. Observations show that the fruit is consumed by boars, and their droppings disperse seeds across the habitat. This mechanism has allowed seeds to germinate after passage through the animal’s digestive system.
Seeds from fruits consumed by wildlife have successfully grown in new locations, contributing to the plant’s distribution across the region.
Reference work: nph on line library content cited for further study
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