Probably not many people in Potomac wish that their community looked more like Detroit. What could anybody find of value in a place where great swaths of abandoned properties and crumbling asphalt have been taken over by weeds?
A lot, according to Harvard botanist Peter Del Tredici. He says that these same urban plants, these “weeds,” are also the de facto native vegetation of our built environment. And not just in places with “faltering economies,” such as Detroit.
They are also here in Potomac Village. The trick is to find them.
So with Del Tredici’s field guide Wild Urban Plants of the Northeast in hand, I set off in search of the other, wilder Potomac. Like botanical explorers of yore, I suffered disappointment and had a close brush with disaster. In the end, I found a Garden of Eden where the urban flora was doing what Del Tredici says it does best: protecting the environment, notably the water of our Potomac River.
I began at the Safeway parking lot, where I squeezed my Subaru Forester in between a Cadillac Escalade and a Lincoln Navigator. I did a final check of my backpack — camera equipment, Del Tredici’s field guide, and a candy bar, just in case.
My search began disappointingly. The asphalt and auto landscape was broken only by carefully placed shrubs, four of them per patch of soil.
Nevertheless, one of these shrubs yielded my first find: a jaunty sprig of poison ivy, reaching up to the sun. The field guide said that this native and reviled vine is tolerant of road salt and provides food for wildlife.
Heading across River Road, my luck improved. There, in the , practically under the elbows of motorists waiting for the light to change, spikes of golden flowers nodded in the breeze of every passing car and truck.
These proud plants were yellow sweet clover. My guide said that they improve the soil by fixing nitrogen and breaking up compacted earth with their tough tap roots. Wild garlic, dandelions, and many more hardy residents packed this biological corridor.
I finished crossing the road and turned back behind Walgreens. In the distance, I spotted two black vats of kitchen grease and a kitchen employee taking a cigarette break. I went to investigate.
The employee, speaking in Spanish on his cell phone, watched as I identified a shoot of oriental bittersweet growing out of the crack where a brick wall met the asphalt. Its bark is used in Chinese traditional medicine. Next to it grew a pokeweed. My guide informed me that juice from its deep purple berries was used to write the first copy of the Declaration of Independence.
At Mitch and Bill’s Sunoco station, I headed right to the concrete planters by the pumps. Sprouting from them was what I took to be edible lambsquarters. As I chewed a piece of leaf, a motorist with no patience for plant nerds called out, “Excuse me, I’d like to use the pump.”
I kept chewing as I headed for Giant. But now my tongue was stinging. Quick, the guidebook! It turned out that the plant from Mitch and Bill’s was actually a member of the potato family. Other members include such edibles as peppers and tomatoes, and narcotics such as tobacco and locoweed. Some are outright poisonous. The leafy green vegetable I chose as a trail snack was deadly nightshade, a Eurasian native.
I hurried through the Giant parking lot, my tongue still stinging from my ignorance. A woman in a sari was loading bags into the back her Land Rover. A man and his son spoke German as they got out of their Mercedes. Before I had turned the corner to the loading docks, I heard Spanish, Chinese, and Russian.
The homelands of all of these people (with the interesting exception of Latin America) have contributed many plants to our Potomac potpourri. All are ― or once were ― aliens. But each helps to make Potomac the cosmopolitan place it is. Here, almost anyone from anywhere can find a plant that makes them feel at home.
Then, in the distance, I spotted the herbal paradise that was the object of my search. Fittingly, its backdrop was the steeple of the . According to an environmental historian I know, the ranks of the Presbyterians have produced many of this country’s well-known environmentalists: John Muir, Rachel Carson, Edward Abbey, the list goes on.
Lush and unkempt, the weed patch stretched west along River Road just up from the . Tendrils of delicate vetch, originally from Eurasia, wrapped themselves around the erect stems of our native milkweed. The spikes of a relative of the buckwheat scratched my hand as I reached for a sprig of henbit.
Why was this exuberant tangle allowed to grow undisturbed? Why no neatly clipped grass or another mulch-and-pansy flowerbed?
I found the answer in the midst of the tangled plants: two iron grates set in concrete at the bottom of a shallow gully.
This is where the water goes when it rains. Here, the “weeds” ― native and alien species all working together ― filter sediments and other pollutants out of the runoff before it enters the little creek nearby. Eventually the water will flow into the Potomac River.
If a few weeds do a little good, think of how much better things would be with more!