The biggest surprises are the ones growing quietly beneath our feet
For decades, science held that mosses — among Earth's oldest and most resilient land plants — stood apart from the fungal partnerships that sustain nearly all other vegetation. Now, researchers at UC Riverside have found evidence that desert mosses harbor fungi living inside their very cells, a relationship hidden in plain sight across the scorching landscapes of the Mojave and Sonoran. The discovery invites us to reconsider not only what we thought we knew about these ancient survivors, but perhaps the deeper story of how life first learned to endure on dry land.
- A decades-old scientific consensus — that mosses were the lone wolves of the plant kingdom — has been quietly overturned by DNA analysis and microscopy from UC Riverside researchers.
- Mycorrhizal fungi, organisms that cannot survive without a plant host, were found living inside moss cells in extreme desert environments, a relationship never before documented in scientific literature.
- The fungal species inside desert mosses differ from those in cooler, wetter climates and don't match the fungi in surrounding soil, pointing toward something deliberate rather than accidental contamination.
- Branching, arbuscule-like structures spotted inside moss leaves under the microscope suggest an active exchange — though whether nutrients truly flow between partners remains to be confirmed.
- If the symbiosis holds up, it could reframe how life colonized land 470 million years ago and open new pathways for restoring fragile desert ecosystems already threatened by warming and human disturbance.
Mosses are among Earth's most tenacious survivors — capable of desiccating into powder and resurrecting within minutes of rain, colonizing bare rock, and thriving in deserts where little else dares. Yet for all their resilience, science long assumed they worked alone. Unlike the roughly 85 percent of land plants that partner with fungi to extract soil nutrients, all 10,000 known moss species were thought to have no need for such alliances. That consensus has now cracked.
Researchers at UC Riverside, publishing in New Phytologist, found evidence that desert mosses harbor fungi inside their own tissues. Doctoral researcher Kian Kelly spent extended time collecting moss samples across the Mojave and Sonoran deserts — environments where temperatures regularly exceed 100 degrees Fahrenheit — comparing them against mosses from milder climates to see whether harsh conditions shaped the fungi living within. Back in the lab, the team ground up moss tissue and searched for fungal DNA. They found it, and more: mycorrhizal fungi, which cannot survive without a plant partner, were present inside the moss cells themselves. Crucially, the fungal species differed between desert and non-desert mosses, and matched nothing in the surrounding soil — ruling out simple contamination.
To move beyond DNA, Kelly turned to microscopy. After staining moss tissue with a dye that binds to fungi, he observed branching structures inside moss leaves that resembled arbuscules — the tree-shaped formations fungi typically build inside plant roots to exchange nutrients. Because mosses lack roots, these appeared in the leaves instead, and researchers cautiously call them "arbuscule-like." Whether nutrients actually pass between moss and fungus, confirming true symbiosis, remains to be proven.
The stakes of that confirmation are considerable. Mosses are evolutionary relatives of Earth's earliest land plants, and this discovery may shed light on the fungal alliances that helped life escape ancient oceans some 470 million years ago. Closer to the present, desert mosses form critical components of biological soil crusts — fragile communities where a single footprint can take decades to heal. If fungi help mosses endure heat and drought, that relationship might one day guide efforts to restore desert ecosystems under increasing climate pressure. For now, the finding stands as a quiet reminder that the smallest patches of life often hold the largest surprises.
Mosses are among Earth's most stubborn survivors. They can desiccate into what appears to be green powder, then resurrect themselves within minutes of rain. They colonize bare rock, thrive in deserts, and scientists have begun imagining them as pioneers for future Mars settlements. Yet according to research emerging from UC Riverside, these ancient plants have been keeping a secret all along.
For decades, the scientific consensus held firm: mosses were loners. Unlike roughly 85 percent of land plants, which partner with fungi to extract nutrients from soil in exchange for sugars produced through photosynthesis, all 10,000 known moss species were thought to operate independently. They simply didn't need fungal allies. That model held until now. Researchers at UC Riverside, publishing their findings in the journal New Phytologist, have uncovered evidence that desert mosses actually harbor fungi inside their tissues—a relationship never before documented in the scientific literature.
The discovery began in the scorching landscapes of the Mojave and Sonoran deserts, where temperatures regularly exceed 100 degrees Fahrenheit. Kian Kelly, a doctoral researcher, spent long stretches wandering these extreme environments collecting moss samples, searching for matching species across different climates to understand how conditions might shape the fungal communities living within them. He was investigating whether the fungi found inside mosses varied depending on whether the plants grew in harsh desert conditions or in milder regions. The question mattered because understanding such patterns could help predict how climate change might affect mosses as drylands grow hotter and drier.
Back in the laboratory, Kelly and his colleagues ground up moss tissue and searched for fungal DNA. They found it. More striking still, they discovered mycorrhizal fungi—organisms that cannot survive without a plant partner—living inside the moss cells. But the fungal species differed between desert mosses and those from less arid climates. "We suspect that certain fungi are more helpful for surviving hotter, drier climates," Kelly explained. The fungi inside the mosses also did not match the fungal species found in the surrounding soil, suggesting these weren't random contamination or opportunistic scavengers feeding on dead plant matter. Something more intentional appeared to be occurring.
DNA evidence alone, however, cannot prove that fungi actually inhabit living plant tissue. Kelly turned to microscopy. One night, after staining moss tissue with a blue dye that binds specifically to fungi, he looked through the microscope and saw branching fungal structures inside moss cells. "As soon as I saw that, I knew we had something really interesting," he said. The structures resembled arbuscules—the tiny, tree-shaped formations that fungi typically construct inside plant roots to exchange nutrients. Mosses lack roots, so these structures appeared instead in moss leaves. The researchers call them "arbuscule-like" because they differ slightly from the textbook versions found in other plants. Confirming whether nutrients actually move between mosses and fungi will require further study before scientists can officially declare the relationship a true symbiosis.
If the partnership proves genuine, the implications ripple backward through deep time. Mosses are evolutionary cousins to some of Earth's earliest land plants. This discovery might illuminate the kinds of alliances that allowed life to escape ancient oceans and establish itself on dry land roughly 470 million years ago. The finding could also reshape how scientists approach desert restoration. Many desert mosses form essential components of biological soil crusts, communities increasingly threatened by warming and human disturbance. A single footprint can take decades to heal. If fungi help mosses endure heat, drought, or climate stress, researchers believe this relationship might one day inspire strategies to revive struggling desert ecosystems.
For now, the work stands as a reminder that the smallest patches of life often conceal the largest secrets. The desert, as Kelly observed, is full of things people overlook. Sometimes the biggest surprises grow quietly beneath our feet.
Citações Notáveis
We suspect that certain fungi are more helpful for surviving hotter, drier climates— Kian Kelly, UC Riverside doctoral researcher
As soon as I saw that, I knew we had something really interesting— Kian Kelly, describing his first microscopic observation of fungal structures in moss tissue
A Conversa do Hearth Outra perspectiva sobre a história
Why does it matter that mosses have fungi inside them? Aren't mosses already doing fine on their own?
They seem fine until conditions get extreme. In a desert, every advantage matters. If fungi help mosses survive heat and drought, that changes how we think about what makes a plant resilient.
But you said the fungi look different in hot deserts versus cooler places. What does that tell us?
It suggests the relationship isn't random. Different fungi for different climates means mosses might be selecting partners suited to their environment—or the fungi are adapting to the moss. That's the signature of a real partnership.
You mentioned this could explain how plants first colonized land. How does moss fungi help with that?
Mosses are living fossils, structurally similar to those earliest land plants. If they've been partnering with fungi all along, it means fungi may have been the bridge that made life on dry land possible in the first place.
What happens next? How do scientists prove this is actually symbiosis and not just fungi living inside moss?
They need to show nutrients moving both directions—that the moss gains something and the fungi gain something. Right now they have the structures and the DNA. The next step is proving the exchange actually happens.
And if it does?
Then we might finally understand how to help desert ecosystems heal. A footprint in the desert takes decades to recover. If we understand what fungi do for mosses, we might be able to restore damaged soil crusts much faster.