Beatrix Potter, Lichenologist: The Even Lesser-Known Chapter

People who know a little about her know the fungi. They picture the watercolours: the toadstools, the fly agaric, the painstaking work under the microscope. Fewer know that some of that work was not about fungi at all. It was about lichens.

Beatrix Potter the lichenologist is the quietest part of her scientific life. It is a small chapter inside an already small chapter. But it holds her single boldest idea — a guess about what a lichen actually is — and the science took almost a hundred years to catch up with it.

This is the story of that guess, and why so few people have heard it.

---

What a lichen is, in plain words

You have seen lichens without naming them. The grey-green crust on a gravestone. The orange patches on a stone wall. They look like one simple plant. They are not one plant at all.

A lichen is two living things sharing one body. A fungus makes the structure and holds the water. An alga lives inside it. The alga has chlorophyll — the green stuff that turns sunlight into food. The fungus does not. So the alga feeds them both, and the fungus gives it a home. Neither is quite itself without the other.

Today this is in every school textbook. It is the classic example of symbiosis — two species living together for shared gain. In the 1890s it was a heresy. And a shy Englishwoman, working alone, had got most of the way there on her own.

---

How a fungus painter came to the lichens

She did not set out to study lichens. She came to them through the fungi.

By the early 1890s Beatrix Potter had turned her sharp eye on funguses. She painted them, named them, and grew curious about how they reproduced. Her teacher in this was Charles McIntosh, the postman of Inver near Dunkeld — Charlie, as the village knew him. McIntosh (1839–1922) walked many miles a day delivering the mail, and along the way he had made himself one of the finest field naturalists in Perthshire. He was tall, painfully shy, and very learned. She had chased him all one summer for an interview.

Under McIntosh, and later under her uncle the chemist Sir Henry Roscoe, she went deeper than painting. She put spores under the microscope and tried to grow them. The more she looked, the more she noticed something odd. Wherever she found lichens, there always seemed to be algae close by. That was the loose thread. She pulled it.

---

The idea, in her own words

Late in 1896 she wrote two short notes to herself. They are easy to miss. On one day she "found the idea of the lichens." A few days later she had "another IDEA (?) about hybrids."

Behind those plain words sat a real theory. She had come to believe that a lichen was not one organism but two: a fungus and an alga, joined into a single working whole. A dual organism. She also believed the two lived together for mutual benefit. That last word matters. She was reaching for symbiosis — the partnership, not the war.

Most botanists of the day would have laughed. To them a lichen was a single lowly plant — a kind of moss, or an odd fungus, nothing more. The great Linnaeus had filed lichens away as the "poor peasants of the plant world." The idea that two different living things could fuse into one and function as a unit struck them as absurd.

---

The German theory she half-agreed with

Beatrix was not the first to suspect this. One man had said it before her, and been mocked for it.

In 1869 the Swiss botanist Simon Schwendener proposed what became known as the dual hypothesis. From studying how lichens were built, he argued they were all double: a fungus and an alga combined. The science world treated this with contempt. To call a botanist a "Schwendenerist" was an insult.

Beatrix had read at least some of Schwendener. She agreed with his central point — that a lichen was two things in one. But she did not agree with all of it. Schwendener thought one partner lived as a parasite on the other. He saw the fungus as a kind of thief, holding the alga captive.

She doubted that. She suspected the two were complete and independent partners, living together for shared gain — not a master and a prisoner. On this exact point, later science would prove her instinct sound. The relationship is a partnership far more than a robbery.

So her position was its own. She took the German theory, kept the half that was right, and quietly improved the half that was wrong.

---

Carrying it to the experts — and being shown the door

Beatrix did not keep this to herself. She took it to the men whose job was to know.

She went to the Natural History Museum with a lichen she had grown, and asked George Murray, the Keeper of Botany, to name it. He told her it was not a lichen at all — just another jelly-like fungus. She did not contradict him. Instead she got him talking about Schwendener's theory. Then she asked the question that was really on her mind. Why was it that wherever there were lichens, there always seemed to be algae nearby?

Murray would not follow her. Neither would Annie Lorraine Smith, the museum's librarian, who knew lichens well. The idea of symbiosis got no sympathy in that room. Beatrix found the whole thing funny rather than crushing. "Upon the subject of chlorophyll and symbiosis I am afraid I am unpleasant," she wrote, half amused at her own stubbornness. She thought Murray "high-handedly contemptuous of old-fashioned lichenologists." The visit told her one thing for certain: no one else was working on this. She was right. No one was.

At the Royal Botanic Gardens at Kew it went worse. The director, William Thiselton-Dyer, dismissed her drawings without looking at them and called her conclusions "mares' nests." She gave as good as she got. "I informed him," she wrote, "that it would all be in the books in ten years, whether or no, and departed giggling."

George Massee at Kew, to her surprise, "came round altogether" and was ready to believe her "new thing, including Lichens." But the establishment as a whole was closed. The trouble with these botanists, she felt, was that they were classifiers first. They had picked at a few species and never "in the least seen the broad bearings of it." None of them, she wrote, "would ever have found out the bearings of the lichen."

---

Why Beatrix Potter the lichenologist is the least-known of all

The fungi paintings survived. There are hundreds of them, in the Armitt collection at Ambleside, and modern mycologists still use them to identify species. They are a body of work you can hold and see.

The lichen work has almost none of that.

It was never a separate project with its own folder. It lived inside the fungi research — a thread running through her experiments, her museum visits, and her letters to McIntosh. She had a real practical problem too. She could never get enough lichen spores to grow. To prove a lichen could live on its own, she needed to germinate its parts and watch the chlorophyll work. The material was never there in the quantity she needed.

And the one document that might have spelled it all out is gone. In 1897 her uncle Roscoe pushed her work toward the Linnean Society of London. A paper went in — on the germination of fungus spores, not lichens — and as a woman she was not even allowed to read it herself or attend. That paper has never been found. Most scholars think it was burnt with other papers after her death. With no paper to study, the fullest statement of her thinking was lost. What is left are journal jottings, a few letters, and a single famous question to Charlie McIntosh: "Do you know anything about lichens?"

So the lichen chapter is faint by its nature. It was never finished, never published, and barely preserved. That is exactly why it is the even lesser-known story.

---

The verdict that came a century late

For a long time the science world simply forgot her. Then, slowly, it remembered — and changed its mind.

The point Beatrix had reached on her own turned out to be right. Lichens are dual organisms. They live in partnership, much as she suspected, not in the one-sided parasitism Schwendener pictured. The exact nature of that partnership stayed in doubt for nearly a century after she stopped working — but the direction of her guess held.

Her biographer Linda Lear weighs the lichen work carefully. She looks at the journal and the drawings. By that evidence, Lear judges that no one in Britain had argued before Beatrix Potter that lichens were a living partnership. Across all of Europe, only Schwendener in Switzerland had said it sooner. "Not a bad record," Lear writes, "for an amateur." Massee himself came round to the lichen theory by 1911.

In 1997 the Linnean Society made a public gesture toward putting it right. A spokesman acknowledged that she had been "treated scurvily" by members of the Society a hundred years before. The newspapers ran it under headlines like "We were wrong about Beatrix." It was, in its way, an apology — late, and to a woman long dead, but an apology all the same.

She had told Thiselton-Dyer it would be in the books in ten years. She was off on the timing. But she was not wrong.

---

A small chapter that says a lot

The lichen work is tiny next to the rest of her life. No book came of it. No fame in her lifetime. A handful of journal lines and a lost paper are most of what remains.

But it shows you the shape of her mind. She looked harder than the experts. She trusted what she saw over what the books told her to see. On a question the professionals had settled wrongly, the shy amateur with the microscope quietly had it right. The lichens she puzzled over are still on the gravestones and the garden walls — two lives in one body, exactly as she guessed.