Naming Trees

The arboretum at Washington University in St. Louis




During the pandemic, staunch botanists hung “Essential Worker” signs on the big, gracious trees that line Washington University’s Danforth Campus. Consider the oxygen, the shade, the cleansing of the air, the shelter for insects, the feeding of squirrels, the holding of the soil….

The more I learn about trees, the guiltier I feel to not know their names. So I press Stan Braude, professor of practice in biology and curator of the university arboretum, into making a few introductions.

We make an unlikely start: a smallish, still bare fringetree with branches that curve and turn like a ballet dancer’s arms. “I’m just delighted with this,” Braude says. “It is from the olive family, Oleaceae, and native to Missouri. The fruit looks like an olive, so two years ago, I collected them, brined them, and marinated them. I fool people all the time! I’m calling them Ozark olives.”

A month from now, the fringetree will be a cloud of white flowers. That is the joy of this edge along Forsyth Boulevard: its mix of sustainable, deep-root plantings reinvents itself every month or two. “I always think of the tree people’s minds as working on a different time scale,” Braude remarks. That cherry allee between the law school and the Knight Center? Two deep, the branches overarching—and someone had that vision when they were just saplings. They think long-term—but they also have to work on the short time scale to get the sequencing right,” because every season has its own choreography.

We walk a few yards east, because as barter for this tour, I get to help him measure a tree they forgot. The arboretum is keeping a database, tracking every tree’s growth. “This is a pecan,” he says. “We’ll be able to compare the pecans on campus to the same species at Tyson” (a wildlife refuge where the biology department does research). “My estimate is that these will do better, because they have so much space and water and fertilizer. But they also have salt and air pollution….”

Much of the arboretum is edible. Braude has me nibble on a red bud blossom (“It’s a legume!”) which proves far sweeter than its white bud sister, though both of them are pretty on salads. “And you’re not hurting the tree, because you’re eating the flower. The leaves are what the tree needs.” One day, he mentioned Turkish hazelnuts to Chris Anderson, the university horticulturist. Not long after, he found three Turkish hazelnut trees planted outside his office.

“They are growing espaliered apple trees in the McMillan courtyard,” Braude continues, “so there will be a wall of apples. In the Brown courtyard, Chris has strawberries as ornamental. I think in about five years, students are going to be more comfortable eating what they find on campus. The only things they have to spray here are the bagworms, so you can feel safe foraging.”

Next year, he and his students are going to graft apples onto crabapple root stock, something they tried once with no success. Cody Azotea, who consults with the university on sustainability for Focal Pointe Outdoor Solutions—“and who puts so much thought into his work that his signature is all over the landscape,” Braude murmurs—has advised him to collect the scion wood when the tree is still dormant. “You put it in the fridge, and then you do your grafting just as the tree is waking up.”

Past rows of hornbeam, as precisely linear as the new Weil building they will shade, we reach the future allee of east campus. The giant pin oaks have been replaced by an alternating mix of Kentucky coffee trees and other kinds of oaks, and eventually they, too, will tower—but more sustainably. “We have gotten very careful about not planting a huge number of the same species,” which risks blight and a total wipe-out.

“This one is overcup oak,” he says, one hand fondly on its trunk. “The cup grows almost completely over the acorn. The leaf is skinny, not as lobed as the classic red or white oak. And this one”—he moves to the next tree, a triumphant lilt in his voice—“is an accident. It is a hybrid. And I love it because the acorns are edible right off the ground.” Their sweetness is rare. Usually, when Braude makes acorn flour with his students (he calls it his Tom Sawyer moment, graciously allowing them to do all the work), the acorns have to be ground down to rice size and placed in an old canvas bag that acts like a teabag, so they can be soaked and squeezed, soaked and squeezed, until finally all the bitter brown tannin has rinsed away.

“These are all serviceberries,” he says as we start to walk uphill, “and they’re delicious. But you have to wait until the red berries turn purple, and then you only have a day or two to grab them before the birds clean them off.”

We reach the east courtyard of Rudolph Hall, aka the magnolia garden. A young Ashe’s magnolia has joined the other magnolias to save its life; native to Florida, the species is now endangered there.

An older tree, not a magnolia and perhaps feeling a little out of place, peeks shyly from the corner of the building. Watson to Braude’s Holmes, I watch as he considers the margin of the leaf, the direction of the veins, the multiple trunks, the bark. It could have been an elder, but, no, it is an Ozark witch hazel tree.

Without segue, he bends and picks up something—a berry? “Rabbit poop,” he announces. “The chickenwire around the new trees is not so pretty, but we have so many rabbits, and they like young trees and will kill them. Next year, we might not have this problem. There is a pair of red-tail hawks on the roof of North Brookings. A student sent me a picture of one of them eating a rabbit on the roof of Ridgley.” He smiles. “I like the way Cody put it: ‘Maybe the hawks will get the rabbits into balance.’”

Students have been counting squirrel nests—those, too, are declining, perhaps courtesy of the hawks—and they will be working with Gerardo Camillo, a Saint Louis University professor who is a world-famous urban bee expert, to sample for bees on campus, giving additional biodiversity data to the office of sustainability. “Arboretum” is not just a fancy name for a place with a lot of trees; the campus uses its trees for education, research, and outreach.

Also sentiment. The first and oldest tree on campus is an American linden/basswood that looks down on the gothic spires of Brookings Hall. “Basswood” is a bastardization of “buzzwood,” Braude tells me, because these trees grow big, then hollow out, and bees hive in them. “So this is both sweet and creepy: Cody took scion wood from this tree a few years ago, grafted it onto basswood root stock, and got seventeen of twenty to take. Three of those trees are now planted at the other three corners of this quadrangle.”

I scan the quad, happy to hear of the three siblings. “What’s creepy about that?”

He shrugs. “It’s not letting this tree die. It’s like cloning your dog.”

Nodding, I fall silent, wondering why that had not even struck me. To me, the trees were still furnishings, though named and admired and storied. But to Braude, they were particular living beings.

The tour could go on—more than two hundred tree species are planted on this campus, with almost six thousand individual, registered specimens. We have not gone near Gingko Allee, where the rancid fruit of this Jurassic species wrinkles undergraduate noses every autumn. We missed the white oak outside Hillman Hall that was propagated from a “trail marker tree” in Illinois. It was deliberately bent long ago, and the Buder Center for American Indian Studies is consulting with people in First Nations to decide whether to bend the new tree, in homage.

Nor have we visited the tulip poplar that came from a tree George Washington planted at Mount Vernon. At least, that is what its plaque says. “I’m sure the actual planting was done by enslaved people,” Braude murmurs, “but I think that problematic plaque should remain, because it opens the discussion.”

He turns us back toward McDonnell Hall. Near his office, display cases that stood empty for years are now filled with gorgeous botanical pressings of the campus trees. Students made them for fun and did it the old-fashioned way, using heavy books to press and dental floss to sew branches and acorns into place. The tracings of veins, the scalloped leaf edges, the rough of the bark, are all carefully preserved behind glass, ready for study.

But outside, they are keeping us alive.


Read more by Jeannette Cooperman here.