A new study released by the Royal Botanic Gardens, Kew and partners describes a rare palm species with an incredibly surprising flowering method.
Native to the tropical island of Borneo, the Pinanga subterranea fruits and flowers almost entirely underground, a phenomenon only recorded so far in one other plant group (an orchid, Rhizanthella).
The palm is well-known by the locals, who snack on the bright red subterranean fruit. But scientists had not realised the importance of the plant until now. Pinanga subterranea was known by the terms Pinang Tanah, Pinang Pipit, Muring Pelandok, and Tudong Pelandok in at least three Bornean languages.
Researchers were first alerted to the plant by the new study co-author Dr Paul Chair, a Malaysian botanist. He first encountered the palm in 1997 and in 2018 Kew scientists Benedikt Kuhnhauser, Peter Petoe and William Baker collected several specimens for scientific research on a field trip.
Most flowering plants flower and fruit above ground, where their seeds can be easily dispersed. A small subset of plants have evolved to flower and fruit underground, in a process known as geoflory and geocarpy. These have been observed in at least 171 species across 89 genera and 33 plant families. A more common example is the peanut which flowers above ground, but its fruit develop under the ground. But fruiting and flowering entirely underground is very rare.
In the case of Pinanga subterranea, scientists have discovered that the plant's seeds are dug up and consumed by the bearded pig. But they are baffled as to how the plant pollinates.
Dr Benedikt Kuhnhäuser, future leader Fellow at RBG Kew, says: “Without the tip-off from our Malaysian colleague Dr Paul Chai, we probably would have mistaken this exciting new species for an unremarkable palm seedling and would have walked right past it. Instead, we have scientifically described an incredibly rare case of geoflory, that is underground flowering, and the very first known example of its kind in the entire palm family. It truly is a once-in-a-lifetime discovery.”
The study was published in the journal PALMS – the Journal of the International Palm Society, with added commentary in Plants, People, Planet.
