In the damp shade beneath moss-covered trees, high in the mountains of Taiwan and mainland Japan or deep within the subtropical forests of Okinawa, an unusual organism quietly grows. At first glance, it resembles a mushroom. In reality, it is a plant called Balanophora, and it possesses some of the smallest flowers and seeds known in the plant world.
Unlike most plants, Balanophora contains no chlorophyll and cannot perform photosynthesis. It also lacks a conventional root system to draw water from the soil. Instead, it survives entirely by attaching itself to the roots of specific nearby trees and stealing the nutrients it needs. Some species and populations take this strangeness even further by producing seeds without fertilization — a reproductive strategy that is extremely rare among plants.
Scientists uncover the secrets of a long-mysterious plant
The genus Balanophora takes its name from its acorn-like appearance (Greek: balanos, acorn; phoros, bearing), and it has puzzled scientists for generations. Because the plant is rare and restricted to highly specific habitats that are increasingly threatened by human activity, most research has been limited to isolated populations.
That is now changing. A collaborative team from the Okinawa Institute of Science and Technology (OIST), Kobe University, and the University of Taipei has conducted a broad survey of Balanophora across its scattered and hard-to-reach habitats. Their findings, published in New Phytologist, trace the plant’s evolutionary history, reveal how its internal structures have adapted to a parasitic lifestyle, and open new doors for future research into this unusual lineage.
As study lead author Dr. Petra Svetlikova, Science and Technology Associate at OIST, explains: “Balanophora has lost much of what defines it as a plant, but retained enough to function as a parasite. It’s a fascinating example of how something so strange can evolve from an ancestor that looked like a normal plant with leaves and a normal root system.”
Shrinking plastids and life without photosynthesis
Parasitic plants often undergo dramatic internal changes as they become more dependent on their hosts. One common trend is the reduction or loss of plastids — a category of plant organelles that includes chloroplasts, which enable photosynthesis in most plants.
Even though Balanophora relies completely on its host trees for nutrition, the researchers found that it has not eliminated its plastids. Instead, these structures have been pared down to a minimal form. While non-parasitic plants may use up to 200 genes to build and maintain plastids, Balanophora retains only about 20. Despite this extreme reduction, more than 700 proteins are still transported into these plastids from the surrounding cell, indicating that they continue to perform essential functions.
Professor Filip Husnik, head of the Evolution, Cell Biology, and Symbiosis Unit at OIST, notes the surprise of this discovery. “That Balanophora plastids are still involved in the biosynthesis of many compounds unrelated to photosynthesis was surprising. It implies that the order and timing of plastid reduction in non-photosynthetic plants is similar to other eukaryotes, such as the malaria-causing parasite, Plasmodium, which originated from a photosynthetic ancestor.”
An ancient lineage shaped by islands
By examining samples from many different populations, the team reconstructed the evolutionary tree of Balanophora and traced how it spread across subtropical regions of East Asia. The plant belongs to the family Balanophoraceae, one of the oldest known groups of fully parasitic plants.
This family began diversifying during the mid-Cretaceous period, roughly 100 million years ago — making it one of the earliest land plant lineages to abandon photosynthesis entirely.
Reproduction without sex and the risks of survival
Balanophora‘s reproductive strategies are just as unusual as its appearance and lifestyle. Reproductive methods vary widely between species and even between populations. Some require fertilization to produce seeds, while others can also reproduce without fertilization, a process known as facultative agamospermy. In the most extreme cases, some species are obligately agamospermous, meaning they never reproduce sexually at all.
“Obligate agamospermy is exceedingly rare in the plant kingdom, because it typically carries a lot of negative downsides — lack of genetic diversity, accumulation of bad mutations, dependence on specific conditions, higher extinction risk, and so on,” says Dr. Svetlikova. “Fascinatingly, we found that the obligately agamospermous Balanophora species were all island species — and we speculate that more Balanophora species may be facultative, or even obligate, agamosperms.”
One advantage of this reproductive approach is that a single female plant can establish a new population after reaching an island. This ability allows Balanophora to spread quickly into the narrow ecological niche it prefers: dark, moist forest undergrowth where few other plants can survive.
A fragile future for a highly specialized plant
Despite its ability to clone itself, Balanophora is extremely selective about its hosts. Each population typically parasitizes only a small number of tree species. This specialization makes the plant especially vulnerable to environmental change.
Dr. Svetlikova emphasizes the importance of collaboration and conservation. “We’re very thankful to our collaborators Dr. Huei-Jiun Su and Dr. Kenji Suetsugu, experts on parasitic plants, for their help in sampling the studied Balanophora species, and to local authorities in Okinawa that allowed us to study these extraordinary plants,” she says. “Most known habitats of Balanophora are protected in Okinawa, but the populations face extinction by logging and unauthorized collection. We hope to learn as much as we can about this fantastic, ancient plant before it’s too late. It serves as a reminder of how evolution continues to surprise us.”
