Anna McLoud Gibbs

Coming This Week: The Story of the Azolla Fern

In summer 2018, I interned at an environmental radio show called Living on Earth. Towards the end of the internship, I was assigned to write a 300-word segment on the Azolla fern. Simple enough. But the more I researched the tiny aquatic fern, the less possible it felt to write only 300 words about this plant. First, I learned that, 50 million years ago, the fern grew in a mat on the Arctic Ocean. But then I learned that the mat was the size of Europe. And that the fern can double its biomass every two days. Because it has a one-of-its-kind symbiosis with a bacteria. Which allows it to pull tons of carbon dioxide out of the air. And because the fern was on an ocean, when it died, it didn’t decompose and re-release the carbon into the air – it sank, and so did the carbon dioxide. Scientists think that the fern pulled trillions of tons of carbon dioxide out of the air and under the ocean. More than half of all atmospheric carbon at the time. Azolla may have played a big role in cooling the planet to its temperate temperatures today: pretty insane.

But if Azolla accomplished that 50 million years ago, what has it done since? Turns out that its resume is long. Farmers in China have used Azolla as a natural fertilizer in rice paddies for millennia. Azolla is also great at filtering contaminants out of water. In Iran, it’s used in nuclear plants to filter the radioactive wastewater. People are using Azolla to cook. People are using it to make soil. And it’s been to outer space. Some researchers think it could be grown on Mars someday as a superfood — 

My editor at Living on Earth made me cut that last fact about Mars. In fact, I had to cut out most of Azolla’s attributes from my segment because there simply wasn’t enough room in the word count. 

Azolla fern. Credit: Fay-Wei Li.

That fall, I took my first science journalism course with Michael Pollan, and we had to write a feature article as our capstone project. I researched local labs at Harvard and MIT, but the Azolla fern kept popping up in the back of my mind. It didn’t feel like the right choice at first. Despite a global effort to sequence Azolla’s genome (literally, global), no one was actively studying the fern nearby where I was, in Boston. I felt far away from my subject. But eventually I was introduced to the new Azolla sample recently acquired by the Harvard Herbaria. And then I was introduced to one of the leading Azolla experts. Who introduced me to another, who introduced me to the next one. Truly, one of the coolest things about Azolla (and that’s saying a lot) is its dedicated band of followers.

Thus my quest began. I talked to Azolla acolytes in Canada, England, North Carolina, Portugal, and the Netherlands. This was my first feature story, my first time interviewing people for a topic that I had sought after — I was learning on my feet, falling in love with narrative journalism, falling in love with this fern. 

At a holiday cocktail party, I found myself extolling the fern’s virtues for much too long than it is socially acceptable. But I was enchanted. I was also learning, however, that to do proper credit for your subject, you have to be critical of it. I didn’t want my feature to be sweeping praise of Azolla. If anything, there were too many of those stories about Azolla already. It made the fern hard to take seriously. If the plant was so great, why have we never heard of it? Why isn’t it grown everywhere? I wanted to look fairly at Azolla so readers could judge it for themselves. Of course, I still hoped in my heart that Azolla would turn out to be, despite its flaws, fantastic. 

When I handed in my first draft of my Azolla story, it was nearly 10,000 words, way too long. I struggled to shorten it. In his comments, Michael Pollan called it “baggy.” And he gave me some of the best advice I’ve ever received when it comes to writing researched pieces, saying: “You wrote a field. Now carve a path through it.” 

Michael Pollen also encouraged me to look at Azolla as a human subject that could be personified. It wasn’t hard to imagine Azolla as a person, given its abilities. I’ll always think of Azolla as my first subject. 

With a lot of peer reviewers (my dad read probably a dozen different drafts), I created a story I was proud of, and one that I thought Azolla would be proud of too. And this week, two years after its inception, the story will finally be told. Keep an eye out at in the next day or two. 

I hope you come to love Azolla as much as I do.

I took home my own Azolla, the smaller reddish leaves in the top left. The fern in the bottom middle belongs to the Salvinia genus.