A New Invasive Plant at Princeton High School

Here's a story about how an invasive nonnative plant can be accidentally introduced and quietly transform an area. It also shows how invasion can be regional but also very localized.

This is a big picture of a little yellow flower called birdsfoot trefoil (Lotus corniculatus). The clusters of flowers and especially the subsequent seedpods resemble the shape of bird's feet, and the tiny leaves echo this shape to some extent.

I hadn't knowingly seen it much, and only learned the name a couple years ago, but this year, 

it has spread aggressively along the grassy extension along Walnut Street at Princeton High School. I'd noticed a few the year before, but now it is dominant along a stretch in front of the Performing Arts wing and the Ecolab wetland. 

This year also, it is coating areas of an old pasture next to Herrontown Woods. In the pasture, it was probably planted intentionally as forage for cattle, but at the school, it surely was introduced accidentally.

Should we be concerned about either example of this nonnative rampancy? I sent an inquiry to a couple listserves of land managers, and received a tepid response. Birdsfoot trefoil is mostly a roadside weed, was the sentiment. It only gets a couple feet high, so will likely just stay in the background rather than stifle native species. 

But I have a vivid memory of a prairie walk I went on last year at the Kishwauketoe nature preserve in my home town in Wisconsin. At one point, leading us through a gloriously restored prairie, the botanist spotted a birdsfoot trefoil and immediately went over and pulled it out. Was it merely a pet peeve, or was his determination rooted in past observations of dramatic consequences if birdsfoot trefoil is allowed to spread? 

This short video shows how birdsfoot trefoil can alter the appearance, if not necessarily the composition, of a meadow:

I did a quick survey of school grounds and the nearby neighborhood by bicycle, and discovered that the infestation is limited to grass next to the extra wide sidewalks that were installed along Walnut Street a couple years ago. It probably hitchiked in on machinery or soil used in construction of the sidewalk. Another possible vector was the planting of new street trees right where the birdsfoot trefoil growth is now the most dense. Rootballs, topsoil, tools, heavy equipment--all can carry weedseeds.

This is an invasion that's in the very early stages, and could be easily nipped in the bud. For instance, I found a grand total of three plants on the middle school grounds. Five minutes of spot spraying with a selective herbicide now is all it would take to stop an infestation that will otherwise become intractable.

Another reason to take action is that it is poised to invade the new native meadow planting in the detention basin next to the tennis courts. In this photo, a few plants of birdsfoot trefoil grow just across the parking lot from the new native planting. Does the school want a native meadow, or a meadow that is thick with a nonnative species that appears capable of outcompeting many of the native grassland plants? 

Now, while the extent of the spread is limited, would be the time to take proactive action. 

PHS Ecolab Wetland Update -- Early June

The Princeton High School Ecolab wetland continues to bounce back nicely from its surprise defoliation last fall. 

If you pass by, you'll see the cattails that we're hoping to keep contained in one corner. The cloud of gray-green beyond is an annual grass planted by contractors as a cover crop, dotted with the deeper green of all the pre-existing native plants now re-emerging from their roots.

The ponds have water, despite the extended drought--sign that the sump pumps are now functioning again, delivering water from the school's basement up into the wetland. 

If you look a little closer, you may see some native blue-flag irises still blooming, happy as clams in this wet world.

On drier ground, the common milkweed is about to bloom.

Bindweed, in the morning glory family, is advertising its location. It's a non-native vine that is too aggressive. While I went around pulling it out (if we could use herbicide, we could kill its roots and be freed of an ongoing task), I checked to see what other plants are rebounding. 

Joe Pye Weed is back, as is fringed sedge.

Good to see boneset and Hibiscus popping up. They don't look like much now, but a (wild) gardener can see the promise in these little nubbins.

It can be a challenge to distinguish a blackhaw viburnum sprout from

silky dogwood. Both of these, along with elderberries, will grow back from their roots to become big shrubs. Since trees become oversized for the site, these shrubs will have to do as places for birds to land and hide. Large shrubs will also help curb the expansionist tendencies of cattails. 

We'll see how the lack of shade, now that trees have been removed, will affect the balance of the various species. Some plants like cattails and lizard's tail may spread more aggressively now that they are in full sun. But overall, the rebound is looking good.

Documenting the PHS Ecolab's Recovery From Last Year's Trauma

Passerby on Walnut Street may have noticed that the Princeton High School Ecolab wetland was completely stripped of vegetation by an outside contractor this past November. After the shock of having so many native shrubs and wildflowers suddenly gone, it took us awhile to realize that the roots of the native plants might still be alive beneath the bare dirt. Having lobbied successfully to have stewardship of the Ecolab returned to the teachers, students, and volunteers who had cared for it free of charge for fifteen years, we are watching for signs of its rebirth. 

Most obvious is the annual grass planted by the contractor for erosion control. But I took a closer look and found gratifying evidence that the wetland will rebound. Click on "Read more" below to see a photo inventory of 40 native species (and a few very manageable weeds) that have popped up thus far, ready to refoliate this wonderful teaching resource for the school's environmental science program.

The Life, Death, and Rebirth of the PHS Ecolab Wetland

On Nov. 6 this past fall, I was returning from a California tour with a latin/jazz band, feeling celebratory. The tour had gone well, but then I received word that something in Princeton had happened that would spoil the return. This is what I found the next morning. The Princeton High School Ecolab wetland had been stripped of vegetation. 

For the past fifteen years, since being converted from turfgrass to native habitat, the wetland has looked like this, packed with more than 30 species of native wildflowers, sedges, rushes, and shrubs like silky dogwood, elderberry, buttonbush, and swamp rose. Though packed with native vegetation, the Ecolab has continued to perform its function of collecting runoff from surrounding roofs and then releasing that water into the town's system of storm drains. Long ago, I learned from experience that native plants thrive in wet, sunny places. The Ecolab is a stellar example. 

Over the years, the magic of this planting has resided not only in the periodic infusions of runoff from the school roof, but also in the sump pump, nicknamed "Old Faithful", which consistently delivered a gift of water from the school's footings into the Ecolab every 20 minutes or so, keeping the wetland wet even through droughts. 

That consistent moisture has sustained frogs and crayfish, and even a very rarely encountered native plant called the marsh marigold. Through those fifteen years, the PHS Ecolab had been Princeton's premier demonstration of how to use water in the landscape before sending it down a pipe to Carnegie Lake. As its name suggests, it has also been used as a teaching tool by the highschool's environmental science teachers.

The project was in-house from the beginning. In 2006, seeing how lawnmowers struggled to cut the grass in this very wet detention basin, I contacted environmental science teacher Tim Anderson and school board member Charlotte Bialek, and together we got permission from the school to create what became known as the Ecolab wetland. High school students designed a series of three ponds for water to flow through on its way through the basin. The grounds crew dug the ponds, and students, teachers, and I dug "littoral" shelves around the edges of the pond, for plants that like to grow near water but not in it. The received important help from a federal agency, Partners for Fish and Wildlife, in shifting from turf to native vegetation, but that help was brief and freely given. 

Over the years, students, teachers, and I have managed the vegetation, keeping out invasive species and discouraging the more aggressive natives like cattails.

In the fall of 2021, Jim Smirk and other environmental science teachers invited me to speak to their students about the wetland's functioning and history. Teachers were excited about expanding the use of the wetland in their curriculum, and converting another detention basin on school grounds to native habitat for study. 

So, what happened? 

How did we end up with a big machine and bare dirt where a wetland had flourished? 

The answer resides deep in the nature of institutions and how they tend to view nature. While the teachers, students, and I were viewing the ecolab wetland's native diversity as a richness and an opportunity, another part of the school--in central administrative offices distant from the high school--was viewing all that lush, complex native growth with a less friendly eye. 

Ask yourself why the lawn continues to dominate our suburban landscapes. For those of us who love nature in all its complexity, a lawn is boring. But for others, nature's complexity is disturbing, confusing, intimidating, and must be fought against. A grounds crew's job is to subdue and simplify nature, not to nurture and work with it. Thus, two very different and opposing narratives about the Ecolab have thrived for more than a decade in different "silos" of the school system.

What finally brought these two opposing views into direct conflict was trees. The Ecolab was originally planted without trees, so as not to pose a threat to surrounding buildings. But at some point, a few willows sprouted on their own and were allowed to grow, on the premise that they would benefit the birds by adding structure to the habitat. When the trees got too big for volunteers to cut down, we asked the facilities department to remove them. Those periodic requests over a number of years, by phone message or email, did not gain a response. It didn't make sense. Here we were maintaining a useful, attractive wetland on school grounds for free. Why couldn't the facilities department help out by removing the trees that had become too large? We grew discouraged.

Though all our work and the teachers' enthusiasm for utilizing the Ecolab for educational purposes were widely known and praised, the counter narrative gained momentum in the school system's distant administrative offices. There, the Ecolab was portrayed as degraded, overgrown, and overrun by invasive species--too much for mere volunteers to care for. Despite awareness that the Ecolab was used for educational purposes, no one invited the teachers and volunteers to participate in decision-making. 

This past summer, unbeknownst to us, a proposal was solicited from an outside landscape contractor who had come highly recommended. In late summer, I caught wind that actions were being considered for the Ecolab, and asked to see the proposal. I submitted a detailed critique, stating that the proposal to give the Ecolab a "reboot" was deeply flawed and lacked a basic understanding of the Ecolab and how it functions. Others gave input as well, about how important the Ecolab is for educating students.

But this last-minute input was not sufficient to break the institutional momentum. The outside contractor was hired, and proceeded to use a disastrous approach. Instead of taking time to learn about the Ecolab's native vegetation and unique functioning, the contractor decided to act first and assess later. Instead of selectively cutting the trees with a chain saw, they brought in a backhoe and other heavy equipment. 

They came on a Saturday, Nov. 5, and by the end of the day, every bit of vegetation had been removed except for two buttonbushes rising incongruously from the bare dirt. Reportedly, not even the high school principal had been given notice. The devastation caught everyone by surprise, even those who had paid the contractor $18,000 for their services. 

For years, the Ecolab has generated a variety of reactions. For those of us who are comfortable with managing a complex planting with more than 30 native species, the Ecolab has been a treasured oasis of natural splendor for students to appreciate and study. For others who prefer the simplicity and clean look of turfgrass, it has been a disturbing presence on an otherwise neatly manicured school grounds. 

Perhaps growing out of that discomfort, attempts were made in the past to falsely blame the Ecolab's vegetation for school flooding. This misdiagnosis proved very costly to the school system. The high school suffered catastrophic flooding twice, causing extensive damage in the basement and requiring replacement on both occasions of the performing arts stage, after flooding warped the wood flooring. The environmental science teacher at the time, Tim Anderson, and I assembled compelling evidence to show that flooding was caused not by foliage in the detention basin but by water surging in towards the school from Walnut Street. So when an outside contractor came in this past November, claiming the Ecolab was full of invasive species and in need of a "reboot," it was just one more misrepresentation of this unique planting. 

Ideally, a traumatic event like this can become a teachable moment. In the months since, the reaching across silos has finally taken place. Apologies have been made to those of us--teachers and volunteers--whose work and knowledge had not been appreciated. 

I and others have been meeting with members of the Operations Committee, teachers, and schoolboard to get the Ecolab back on track. One day, discussing the Ecolab with other volunteers and the school's Public Information Officer, Elizabeth Collier, looking for a positive way forward, an idea came to mind. Why not use the clearing of the wetland as an experiment in regeneration? Though the contractor did some digging, most of the soil is still intact. Much of the diverse native vegetation would likely resprout come spring. Teachers and their students could then witness the rebound of a wetland from dramatic disturbance, and take part in actively managing the vegetation as it rebounds, removing any tree sprouts and other aggressive species, and adding additional natives in bare areas. 

The central administrators seem now to be listening to the environmental science teachers and others of us who are the most knowledgeable about the Ecolab's functioning and have been the most invested in its ongoing care. 

Update - May 2023

The latest I've heard is that the outside contractor will no longer be involved in the Ecolab. Presumably, this means that management of the vegetation will once again be done by the teachers, students, and knowledgeable volunteers. The school's operations department continues work to repair the sump pump that had been supplying the Ecolab for more than a decade with water even during droughts. "Old Faithful" apparently got old, and stopped working a year or two ago.

As hoped, the native vegetation has begun to rebound. First to reemerge were the marsh marigolds, one of which bloomed, surrounded by what still appeared to be lifeless dirt. The poignancy of this bloom brought back memories of James Thurber's The Last Flower, a story about how, after terrible destruction, the last flower on earth became the first of many. Plants play a similar role in the movie Wall-E.

I compiled a list of lessons learned. 

Institutional Silos -- This tale certainly speaks to how conflicting narratives can spring up in different parts of a large institution like a school system.

The Invisibility of Volunteers -- Our work as volunteers over fifteen years to maintain the Ecolab remained essentially invisible to the powers that be. Emails and phone calls were not enough. Until we began showing up at official committee meetings--essentially reaching beyond our silo--we did not exist. 

Devaluing that which is freely given -- In a lifetime of working with nature, I've seen how nature gives freely, and how all that generosity can be taken for granted, and be undervalued in a society that often judges value in monetary terms. Expertise and stewardship, too, can be undervalued if it's local and freely given, without any formal written agreement. 

The false security of hiring professionals -- It is astonishing just how incompetent the professional landscape company proved to be, despite being highly recommended by a highly regarded area environmental nonprofit. I've seen less extreme examples before, in which an outside contractor is brought in with disappointing results. Regardless of professional reputation, they lack the time to gain an intimate understanding of a local site, particularly one with unique qualities like the Ecolab. Unlike local volunteers who care about the school and the community, an outside firm has no "skin in the game" beyond fulfilling a contract. Spending money on professionals brings no guarantee of desired results. 

Managing nature's complexity -- There is an initiative to add additional complex plantings such as food forests to Princeton's highschool and middle school grounds. Having educational plantings on school grounds is convenient for teachers who would otherwise face the logistical challenge and expense of transporting classes to distant locales. A good model for growing complex botanical plantings on school grounds is the Princeton School Gardens Cooperative, which hires quarter time educators/stewards to oversee care of five school vegetable gardens. For this next initiative, it will be important to acknowledge that a grounds crew is typically focused on maintaining simplified landscapes of trees and turf, and that a separate caretaker who understands and cares about nature's complexity is needed for educational plantings. The grounds crew could, however, play a valuable role,  but only in a collaborative way with a skilled caretaker. 

Solarizing a Princeton High School Detention Basin

Earlier this fall, I was passing by Princeton High School on Walnut Street when I saw something I'd never seen before: 

a whole field covered with plastic. The field, next to the tennis courts and a parking lot, is actually a stormwater detention basin that the school wants to replant as native meadow. But before planting, they need to kill the existing turfgrass. 

I had contacted the schoolboard members on the Operations committee a number of times over the past year, promoting the meadow idea and encouraged them to contact a federal agency called Partners for Fish and Wildlife. Over the years, I had worked with Partners to convert, at no cost, a number of detention basins in town to native meadow--at Farmview Fields, Smoyer Park, Greenway Meadows, and even at the Princeton High School ecolab just down Walnut Street. 

Instead, the school hired at some expense an outside contractor to do the conversion. The plastic is probably a very plasticky attempt to avoid the use of herbicide. If you place clear plastic over grass, the heat from the sun gets trapped under the plastic. Like a greenhouse, or the earth's atmosphere, or the windows of a car parked in the summer sun, the clear plastic is transparent for light but opaque for heat. The sunlight travels through the plastic, hits the ground, turns into heat, and the plastic keeps the heat from escaping. Trapping solar heat to kill the grass is called solarization. I had accidentally done something similar when I laid a vinyl floormat on the grass next to the curb in the hopes someone else would find it useful. No one took it, and the grass under the mat was killed, leaving a brown spot for the rest of the summer.

This PHS environmental science teacher is one of several using this detention basin as well as the ecolab to teach about stormwater issues and habitats. 

Unfortunately, the plastic was installed late in the summer, as the sun's power was waning. When the plastic was removed this week, the results were less than impressive. A deep-rooted weed called plantain remains particularly abundant. 

It would be interesting to find out why herbicides were not used. The school may well have banned the use of herbicides when school is in session, but that doesn't preclude the use after hours or on weekends. Herbicides get a bad reputation for being heavily used to impose sterile lawns in suburbia, or on farms to eliminate every last weed, including milkweed. But they can also be used, in a targeted, minimalist, medicinal way, to kill invasive weeds that would otherwise be too difficult to control physically. We manage toxicity in our own bodies, taking only enough medicine to achieve a beneficial effect. Banning herbicides brings the comfort of absolutism, and makes people feel they're being green, all the while handicapping those who are actually doing the work to restore native diversity to the landscape. 

We'll see how the project goes. Not sure what happened to all of that plastic.

Some Summer Gardening Success at Princeton Schools

There can be a tendency for school gardens to suffer neglect during the summer, but many in Princeton are doing surprisingly well. There are the gardens on the grounds of Riverside Elementary that are best known and continue to flourish, but quite a few others as well. Behind Community Park Elementary, there was a wildflower garden in the courtyard behind the school that over the years got taken over by the most aggressive wildflowers--sunflowers and goldenrods, which have those strong rhizomes that other wildflowers can't compete with. This year, a friend and CP parent, Georgette, decided to renovate the garden and asked me to co-teach an after-school class for the purpose. After a lot of work, some of it done by the kids, who went at it with considerable zest and confidence, the garden now is transformed, with hills of corn planted Indian-style, a tipi trellis for string beans, a few wildflowers and switchgrass from the original planting, and some unusual crops,

like cotton,

and amaranth. The quinoa, not shown, looks a lot like the amaranth, which makes sense since they are both in the Amaranthaceae family. It was interesting to discover that a common edible weed in our summer gardens, lambsquarters, is in the same genus as quinoa: Chenopodium.

Some of the weeds at Community Park, as the photo shows, are hard to reach (hope that's not evidence of some serious deferred maintenance),

but we did manage to pull out enough foxtail grass, pilewort, and velvetleaf (photo) to get the intended plants ready for the opening of school. The velvetleaf, by the way, is in the same family as cotton, the Malvaceae, as is the native Hibiscus in the wetland below.

Now's a good time to take a stroll down Walnut Street and stop by the Princeton High School ecolab wetland. Native hibiscus, joe-pye-weed, wild senna, giant cup-plant all are at a perfect height for viewing from the railing. I was over there the other day and happened upon a woman holding a large bouquet of flowers (bought, not picked from the wetland) and a young man all dressed up and serious, who appeared to be proposing. A proposal of marriage next to our wetland? I think we're onto something with this wetland garden thing.

The wetland was completely unfazed by the recent heavy rains. I just hope the school survived. This fan on the wooden performance stage brings back memories of the flood damage a couple years back, but a sign said they were waxing the floors.

And behind the highschool, the gardens may not be proposal-worthy, but a few of the raised beds are in good shape. Though the bed on the right shows how foxtail grass will take over any bed that's not cared for, the native cutleaf coneflower (tall yellow flower) and New England aster we planted a few years back have expanded to two beds instead of the original one. Some angel gardener must be helping this happen.

The coneflowers in turn will attract more yellow in the form of goldfinches as the seeds begin to ripen.

Visited a month ago, Littlebrook Elementary has a fine crop of milkweed feeding the monarchs, and a nature trail that handyman Andrew Thornton has been tending to with the help of some sophomore volunteers.

Monarchs Bring Dance, Delight and Larger Meanings to a Backyard

These are the glory days for monarch watching, with the backyard packed with flowers--a veritable feast that we are grateful to provide.

Lovely as it is, the levitated landscape of pinks and yellows, reds and whites, gains a deeper meaning when a monarch arrives to animate the garden with its fanciful, danciful flight. Brilliance of color is matched by brilliance of movement, with glides and hairpin turns, sudden dips or dartings upward, gracing a garden's contours as if its flight were a form of affection. With an uncanny mix of power and whimsy, the monarch looks to know what it's looking for, as it approaches then darts away or doubles back, each minute of its flight a hundred instant decisions. What makes it land on one flower after approaching and rejecting so many others, seemingly the same, is a mystery.

This morning we saw four at once, two of which flew together, then collapsed upon the carport roof, there to mate for a minute while I ran to grab my camera. The one in front looks to be the female, with thicker veins and no little black spot on the wing.

This one here is a male, judging from the less prominent veins,

and those little black spots on either side of its abdomen.

The monarchs were especially drawn to the joe-pye-weed that with the summer's heat and rain have grown to ten feet high, like a mountain range of flowers.

Sometimes, when a monarch flew and flew around the garden, looking, looking, I thought it might be searching not for nectar but for a milkweed plant to lay its eggs on. Our swamp milkweed disappeared some years back, and this year my wife bought this kind, with orange and yellow flowers. Turns out to be tropical milkweed, native to Mexico but not here. It's pretty, easy for nurseries to grow, and rebounds quickly if ravenous monarch larva consume its leaves. It's also said to have some aspects, given the nature of its more tropical growth, that would make our northern native species of milkweed a better option,

like this butterflyweed that is flourishing in a neighbor's garden.

Most of Princeton's milkweed is common milkweed, which is less ornamental, spreads underground, and can be found in fields, along roadsides, and in this case growing at the nearby Princeton High School ecolab wetland. Other species include purple milkweed, a few of which grow at Herrontown Woods, and green milkweed, found years back in the meadows at Tusculum.

The dominant ideology of our day has deprived us of the satisfaction of contributing to something beyond ourselves. I grow more garden and less lawn because I love native plants, but the monarchs connect the garden to something much larger. Each March, starting out from their wintering home on just a few acres in the mountain forests of Mexico, the monarchs stretch themselves across all of eastern North America, ambassadors of beauty, as if to tell us that all our small efforts, spread across the land, are additive in and to nature, that we can contribute to something profound. May the monarch teach us how to find that satisfaction in other aspects of our lives as well.

Joe Pye by the End of July

Judging from the corn fields around Princeton, the old adage "knee-high by the 4th of July" needs to be updated. Corn was at least head-high earlier in the month. The rhythm and rhyme can be applied to the classic mid-summer flowers of Princeton's floodplains, whether along the canal towpath or planted ten years ago on the higher ground at the Princeton High School ecolab wetland: JoePye by the End of July. That's Joe Pye Weed, which comes in several species, the most common around here seeming to be hollow-stemmed (not in the photo).

That's rose mallow hibiscus in the background of the first photo, thriving with its feet in water consistently supplied by the school's sump pump.

Wild senna is another classic mid-summer native flower, in the pea family. Planted in this case at the new botanical garden at Herrontown Woods, it has yet to be browsed by the deer. The white spires in the background are Culver's Root, a purchased native that I have yet to encounter growing naturally in NJ.

Another common mid-summer classic is cutleaf coneflower, not shown here, but popping out at the various places we've planted them in town.