Researchers at the Royal Botanic Gardens (RGB), Kew, and their partners have made a remarkable discovery in the natural world. They have found a palm species called Pinanga subterranea that flowers and bears fruit mostly underground. This groundbreaking finding, published in the journal PALMS, reveals the existence of a new species that has been named Pinanga subterranea, meaning ‘underground’ in Latin.
Pinanga subterranea is native to the tropical island of Borneo in Southeast Asia. Despite the plant and its fruit being known to locals for a long time, scientists overlooked it for years. The locals have various names for the plant in different Bornean languages, such as Pinang Tanah, Pinang Pipit, Muring Pelandok, and Tudong Pelandok.
The international team of researchers found that Pinanga subterranea thrives in the primary rainforests of western Borneo, specifically in the borders between Malaysia’s Sarawak and Indonesia’s Kalimantan. The discovery of this plant was brought to the attention of the scientific community by Dr. Paul Chai, a Malaysian colleague of the researchers.
Dr. Benedikt Kuhnhäuser, a member of the research team and a future leader fellow at RGB, Kew, expressed gratitude to Dr. Paul Chai for the tip-off. Without it, they might have mistaken Pinanga subterranea for an ordinary palm seedling. Dr. Kuhnhäuser described the discovery as a once-in-a-lifetime find because Pinanga subterranea is the first known case of underground flowering in the entire palm family.
Most flowering plants develop their flowers and fruits above ground to facilitate pollination and seed dispersal. However, a small group of plants has adapted to perform these processes underground. Pinanga subterranea now joins the ranks of over 2,500 known palm species and at least 171 species across 89 genera and 33 plant families that engage in underground flowering (geoflory) and fruiting (geocarpy).
The dual occurrence of geocarpy and geoflory in Pinanga subterranea baffles researchers. Typically, the Pinanga genus relies on insect pollination, making underground pollination and movement more challenging. The research team observed a significant number of seeds and fruit set by the plant, indicating a successful but mysterious pollination mechanism.
Dr. William Baker, the senior research leader at the Tree of Life project at RBG Kew, expressed astonishment at the discovery. After studying palms for 30 years, he continues to be amazed by their ability to surprise researchers. The revelation raises questions about the identity of the pollinators, how they find the subterranean flowers, and the evolutionary origins of this phenomenon. Dr. Baker eagerly anticipates further revelations about the fascinating world of palms.
Agusti Randi, an Indonesian researcher from the National University of Singapore and the lead author of the study, noted that this was not the first encounter with the palm species. In 2017, Randi came across a few specimens in a forest in West Kalimantan. Some of these specimens were unearthed by wild pigs, while others were likely consumed or crushed by the animals.
During the initial encounter, Agusti Randi found ripe fruits with a vibrant red color on the ground near a population of Pinanga subterranea, while wild boars were digging in the soil. The wild boars had exposed the plant’s stems to access the underground fruit, and their feces contained the palm’s seeds.