USING DNA tests, Japanese researchers have found a hidden life stage of ferns that can live and multiply on its own — without growing leaves or fronds — reshaping species maps and pointing to more undiscovered diversity in the tropics, including the Philippines.
Tokyo Metropolitan University professor emeritus Noriaki Murakami shared this discovery in a lecture in UST, explaining how his team identified independent fern gametophytes, a long-overlooked, self-sustaining life stage that had eluded scientists for decades.
These are tiny, moss-like life forms that represent the gametophyte phase of a fern’s life cycle — the stage responsible for producing reproductive cells.
Unlike the typical leafy, spore-bearing plants seen in gardens or forests, these gametophytes can live for decades without ever developing leaves or stems. Though barely visible to the naked eye, they are living proof that ferns can persist in the most unexpected ways.
Often mistaken for mosses or other non-vascular plants called bryophytes, these miniature ferns reveal how adaptable and diverse the group truly is, challenging long-held assumptions about fern biology and evolution.
Murakami, who has studied ferns since the 1980s, explained that all ferns alternate between two distinct life stages known as alternation of generations. This process allows them to reproduce and adapt to different environments.
The sporophyte is the familiar, leafy stage that produces spores and dominates most fern life cycles while the gametophyte is a smaller, simpler form that produces sperm and egg cells, from which a new sporophyte grows to complete the reproductive cycle.
While most studies have focused on the dominant sporophyte stage, Murakami said his students’ discoveries revealed that the gametophyte, previously believed to be short-lived, can actually endure independently for hundreds of years.
“[The student] reported to me that gametophyte marks are everywhere; not rare, so I was very surprised. I have been studying the ferns for more than 40 years, but I never recognized the fern gametophytes in the field,” he said during his lecture.
The UST Department of Biological Sciences organized the lecture, “The Fern Independent Gametophytes: Ferns That Look Like Bryophytes and Continue to Grow Without Sporophytes,” on Oct. 24 at the Albertus Magnus Auditorium.
Murakami also recalled how one of his students, while hiking through the forests of Okutama in western Tokyo, stumbled upon green mats clinging to shaded rock walls.
To the untrained eye, they looked like ordinary moss. But when the samples were analyzed through DNA barcoding, they turned out to be independent gametophytes of Hymenophyllum mikawanum — an endangered fern species once believed to exist only in central Japan.
The gametophytes not only survived without developing fronds but also flourished in distinct valleys separated by more than a kilometer. This presents an unusual pattern for a plant believed to reproduce via airborne spores.
“It is not easy for [gametophyte] ferns to move to different valleys. It is easy to move along the water stream, but we can easily consider it difficult to move between the different valleys,” Murakami said.
Unlike spores, gemmae are tiny clumps of cells that directly grow into new plants rather than needing fertilization. These small plantlets detach from the parent gametophyte and spread through water runoff instead of drifting in the air.
This method of reproduction, known as vegetative propagation, allows the gametophytes to multiply and survive in shaded, humid environments where full-grown ferns cannot.
“The gametophyte can survive because it is stronger than the sporophyte against cold or dryness. Even if they become dry or freeze, they can divide and continue living.”
Murakami said their findings add to growing evidence that some fern species can persist for thousands of years through this hidden life stage, quietly spreading long after their leafy generations have disappeared.
Beyond this scientific discovery, Murakami also discussed the importance of mentorship and student independence in science, a philosophy he learned from his mentor, Dr. Kunio Iwatsuki, one of Japan’s leading botanists.
Murakami is the director of the Museum of Nature and Human Activities in Hyogo, Japan, where he continues to mentor young botanists and expand his studies on fern evolution and biodiversity.
“My professor, Dr. Iwatsuki stimulated my interest in ferns and gave me the opportunity to study them freely,” Murakami told the Varsitarian.
“Now, I treat my students the same way, supporting their interests rather than imposing mine.”
He said his students’ curiosity and independence have led to many of his lab’s most remarkable findings.
“Students are very important. They are young and much more powerful than us. I got really interesting results with their help — they can do anything.”
For Tokyo Metropolitan University professor emeritus Noriaki Murakami, the discovery of independent gametophytes is a reminder that even the most studied plants still hold mysteries.
“We have a lot to do in the future for plant research. You can make many new findings, [because] humans know only a little about plants.” With reports from Marielle F. Pesa
