I FIRST DISCOVERED MY TREE IN A GRAINY, black-and-white photograph. I was skimming through the internet, inspecting towns outside of Lyon, France, for an article I was writing about the environs of my favorite city. Suddenly, an enormous linden caught my eye. I was immediately struck by how the tree functioned as the actual center of the small-town square from which it rose, its generous canopy throwing a large circle of shade, rendering the square itself an afterthought. I was captivated.

At the time, I was also working on a new novel. The story would follow a woman named Alice and her two daughters—ages eight and thirteen—who travel and camp across France as Alice rediscovers herself in the wake of breast cancer and her husband’s infidelity.

At the time, I didn’t know much more than that; I was feeling my way from the Alps, down to Provence, along the Pyrenees, across the Dordogne River Valley, and back to Lyon.

When I’m writing a novel, it’s as if my pores are opened. I go through a wardrobe and become a tourist in an unfamiliar and intriguing land: I walk slowly. I look at everything. I imagine tasting new foods, smelling new smells, touching things I’ve never felt the likeness of before. Anything and everything, I reason, could become part of the world I’m creating. It was in this state that my linden found me.

PLANTED IN 1438 IN THE SMALL FRENCH TOWN of Samoëns, about 135 miles to the east of Lyon, this particular linden was planted to celebrate a local duke’s gift of a handful of alpine meadows to the town’s inhabitants. This was so long ago that Joan of Arc had just been burned at the stake, Shakespeare was not yet born, and the Medici family was still patronizing Michelangelo. As the tree grew by decades and then centuries, it came to be known, affectionately, predictably, as Gros Tilleul, or Big Linden. I could just hear a child shouting to a friend, “I’ll meet you at the Big Tree after school!”—then waiting in its leafy shade, starlings chittering in the branches above.

Incredibly, Big Linden is still standing. I came to imagine her as a protective grandmother, watching over her little town, the children. She has, undoubtedly, seen fierce storms, flooding, drought, and epic shifts in human impact. Cities and highways have sprung up around her as the planet’s climate has changed, irrevocably.

Contemplating what it would be like to experience this kind of enormous, centuries-long change, I could not stop thinking about her. I pored over every photo I could find, old and recent, studying her bark and branches. I wanted to know more about what she had endured, if she was still healthy. When I saw that she had lost a huge branch, in one image, I felt worry ping inside me, as if I were seeing a loved one injured. From across the world, I had started to really care for Gros Tilleul.

I pored over every photo I could find, old and recent, studying her bark and branches. I wanted to know more about what she had endured, if she was still healthy.

Even today, it’s common knowledge among many Europeans that young linden leaves are tender and delicious when mixed into a salad; that the flowers are a favorite of bees and lend a lovely aroma to their prized linden honey; that tea made from the leaves and flowers helps reduce fevers and relieve anxiety, insomnia, and pain. In France, Tilleul tea is so common that you can buy a box from any regular supermarket. It’s often given to children after dinner to help them digest and sleep. And anyone will tell you about how much the birds love these trees. Indeed, European starlings and lindens are almost synonymous, as the birds often nest in trunk holes and gather in raucous cacophony in the canopy. Insectivores like sparrows and warblers descend in huge flocks to snatch aphids drawn to the tree’s sweet sap.

Like anyone newly smitten, I wanted to know more. I learned from scientific studies that lindens are adept at living in all kinds of conditions, including through drought, high wind, and poor soil. They are uniquely resilient to air pollution and have an unusual ability to sequester large amounts of carbon monoxide in cities. Forward-thinking communities across the globe are planting lindens in urban areas because of their unique air-scrubbing qualities and ability to withstand heat and freezing temperatures throughout their long lives. At night, I would lie awake thinking about the courage of the Big Linden, how much she had witnessed, how many beings to whom she had given shade and comfort. I tried to imagine the cool shadows of her branches on my own skin, bees buzzing all around.

Perhaps it’s no surprise that a fictional version of this Gros Tilleul ended up at the heart of my novel.

PERHAPS IT’S NO SURPRISE THAT fictional version of this Gros Tilleul ended up at the heart of my novel, though I put her in on the banks of the Saône River, to the west of Lyon. Sometimes, as a writer, you don’t realize how your threads may come together and conjure wonderful points of connection. Soon, my three characters were drinking Tilleul tea and eating cake soaked in linden honey and then, at last, on their meandering journey, they arrive at the trunk of a massive linden, and it enchants them as it did me.

Once I placed my tree in that square, I fell even deeper in love. I perfumed my wrists with linden flower essential oil and kept writing. As I neared the end of my book, I realized with surprise, the tree was not just an interesting landmark, but the actual center of my story. She had grown over the course of my writing, branched out, and canopied the entire book.

WEEKS LATER, AFTER I SENT THE NOVEL to my editor, a dear friend called to say she’d found a large old European linden not far from my home in Maine. I leaped at the chance to meet it. The next day, my husband and I drove an hour northeast. It was fall. The sky blue, the air crisp. Planted over 250 years ago, this linden was both old and still young. As I looked up into its magnificent branches and stroked its rough bark, I felt awe. I wanted to protect this being as much as I wanted to accept its protection, even if temporary. In its shade, I told myself that one day I will make the journey to visit Gros Tilleul.

When I imagine our meeting, I see myself running for her like a child, throwing my arms around her trunk.