Botanical Threats to Greenway Meadows--Neighbors Raise Concerns

Over the years I've sung the praises of Greenway Meadows, the park in western Princeton with an asphalt trail running down the middle of an expansive meadow. One post describes the beauty of broomsedge and cross country racers "testing inner nature in a natural setting." Another describes the exhilaration of riding a bike through the meadow on the way to an art exhibit opening at the Johnson Education Center.

More recent visits to Greenway Meadows have focused on the threats to the park posed by invasive species, and the need to act quickly, before the problem gets overwhelming. This past April, it was dramatic to see how lesser celandine is beginning to invade the meadow and the lawn.

Then this summer, Mimi Schwartz, who lives near Greenway Meadows, reached out about the park. She had noticed some attrition among trees along the Poetry Trail, and wondered if competition from the tangle of invasive shrubs growing beneath them might be a cause.

Another neighbor of the park, Jennifer Widner, is focusing on threats to the meadow--threats that surely go unnoticed by the many people who walk or jog down the asphalt trail, see a pleasing green, and look no closer.

Still apparent to all are the many native wildflowers in the field, among them common milkweed and wild bergamot. 

But on a visit to meet Jennifer, I was astonished to see the extent to which Sericea lespedeza (aka Chinese bushclover, Lespedeza cuneata) is beginning to dominate. This is an invasive species that has become a big problem in the southeast U.S. and the plains states, but was comfortingly rare in Princeton when I first moved here in 2003.

There are various species of native bushclover that can sometimes be found mingling with other wildflowers in a field, but Sericea lespedeza doesn't, as they say, "play well with others." It's behavior is more that of a bully.

In understanding the threat posed, it helps to have lived elsewhere in the country where Sericea lespedeza has had a longer track record of aggression. Living in Durham, North Carolina, near where the species was first introduced, in 1896, and is still widely used for erosion control despite many efforts to have it banned from seed mixes, I witnessed its capacity to displace native species. 

For those who say live and let live, and let it be, consider the ecological consequences if the meadow ultimately becomes a monoculture of an introduced plant with indigestible seeds and inedible foliage. Here's one fact sheet's description:

"Sericea contains a high concentration of tannic acid, which causes wild and domestic animals to avoid eating it, unless no other food is available. Animals then forage more intensely on native plants, which depletes the desirables and allows invasives to increase. Tannic acid leaches from sericea into surrounding soil, creating a toxic environment that prevents or slows the growth of other plants, giving it yet one more advantage."

Mimi and Jennifer have had some success engaging public officials on these threats, and the land managers at DR Greenway's headquarters nearby are potential allies. 

The project with the clearest solution is the freeing of trees from the invasive shrubs growing beneath. A greater challenge, requiring intervention and vigilance for years to come, will be stopping uber-invasives like lesser celandine and Sericea lespedeza. 

My experience, though, is that the work can get easier year to year, as steady effort makes the invasives less numerous. Down the road, or down the trail, as the threat recedes, those involved may get to experience that wonderful "walk in the park" feeling, where the botanical bullies have been sent packing, and require only a bit of ongoing vigilance and mild intervention to prevent their return.

For more information on Sericea lespedeza, try these: BlueRidge and Oklahoma State.

Related post:

Monocultures in the Making - 2013

Fuel Tank Raingarden Losing Out to Weeds

Maintenance is looked down upon and taken for granted in our culture. One reason for this is that, done well, maintenance is invisible. Our human tendency is to notice what is wrong, not what is kept right. At home, we are more likely to notice dirt and disarray than the cleanliness and order a housemate worked hard to achieve. 

In landscaping, the tendency is to fund and celebrate design and installation, then leave maintenance to the vicissitudes of chance, undertrained and undermotivated staff, and perennially strapped budgets. But even with the best designs, maintenance is what ultimately matters. Maintenance is destiny. 

Maintenance at its best is a form of love. In gardening, what we call maintenance is really more akin to the nurturance of parenting--an ongoing process of encouraging what is desired, and discouraging what is not. A garden can also be thought of as a playground. When maintenance is done right, plants that exhibit bullying behavior, like mugwort, don't get to play in the garden. 

Environmental groups encourage people to dig up some lawn and plant native wildflowers. These meadow plantings are characterized as low-maintenance, but that is true only if the weeds are caught early. Once the weeds get firmly established, maintenance becomes very difficult.

The only gardens I've seen flourish are those that are loved, like a child is loved. Love leads to knowledge and steady attention, and early intervention when things go wrong. 

Just off Witherspoon Street in Princeton there are contrasting examples of loved and unloved public gardens. 

The loved garden in this instance has almost no weeds--a standard few of us achieve. For years, near the entrance to the Community Pool, gardens around the Princeton Recreation Department offices were taken care of by "Vikki C. and Team PRD," as the sign proudly declares. That would be employee Vikki Caines. Vikki's glorious plantings expanded over the years well beyond the Rec. Dept. building. She retired in 2023, but when I asked her, she assured me that her gardens would continue to be well kept. 
 

By contrast, just down the street, past the Princeton First Aid and Rescue Squad, lies a rain garden that collects water from hard surfaces around the town's fuel storage tank. Regulations require that raingardens be dug and planted to collect and filter runoff from new paved areas. In a series of posts, I've tracked the destiny of this very public but largely unnoticed raingarden, whose extended limbo in 2020 ended with planting in 2021. But in gardening, as when a baby is born, the birth of a garden is not the end but rather just the beginning. In 2022, it was still full of color and easy to weed, but by 2023 the weeds were getting entrenched. 

I alerted town staff that the raingarden was losing out to the weeds, and was told that the municipality was weeding it once or twice a year, and was working "towards a system of regular maintenance, while balancing many, many other priorities."

This year, the original plantings are beginning to disappear beneath waves of mugwort, nutsedge, and other botanical bullies that don't play well with others--

weeds like foxtail grass, 

and wild lettuce--to name just a few of the species that maintenance crews would need to be able to recognize and remove. Note that the designer of a garden must know only the intended plants, while the maintainer, typically underpaid and underappreciated, must additionally know and recognize the many weeds that can invade.

This is the difference between loved and unloved gardens. Imagine a child being notified that a parent was "working towards a system of regular visits, while balancing many, many other priorities."

Now, a town's public works department does of course have many other priorities. Job one is to serve people, not gardens. But that being the case, the aim would be to keep the raingarden in the easy-to-maintain stage by catching the weeds early. Vigilance and early intervention--a form of love--save time. 

The only way Vikki Caines could maintain beautiful gardens while also doing her job in the recreation department was to stay on top of the weeding. 

Well-designed raingardens are easier than most gardens to maintain. The runoff they collect keeps the soil soft for easy weeding, and many native species of wildflowers and shrubs are adapted to flourish in the wet ground. Regulations can call for the digging and planting of raingardens, but the fate of the planting is left to chance. Weeds grow 24/7, while people are easily distracted. If the weeds take over, the ultimate response will be to mow it down and manage it as lawn. Nature's complexity, unloved, unnurtured, will once again be simplified and suppressed, the better to pursue other priorities.

Related posts: 

To Save a Raingarden, Know Your Weeds 

The Work Behind a Natural-Looking Meadow: Smoyer Park in Princeton

Evolved Coexistence in Nature

What is "natural" in nature? I remember a 1990 column entitled "Bug Wars," in which NY Times columnist Anna Quindlin wrote about the gypsy moths that, back then, were defoliating vast areas of eastern forest. She used the destructive moths as fodder for reflections on nature and its ways, not knowing that the moths can hardly be thought of as natural. They were introduced from another continent, then escaped and multiplied, consuming forests that had not evolved any defenses against them. Fortunately, scientists found a very low-toxicity way to limit the gypsy moth's numbers, though sustaining that balance requires ongoing human vigilance and action.

With introduced insects and diseases having decimated first our ashes and now our beech trees, it's worth noting the more sustainable relationships between plants and animals that have co-evolved over millennia on the same continent. 

Tent Caterpillars and Black Cherry

This spring, tent caterpillars defoliated some of our black cherry trees. Were the caterpillars a threat to the trees? Well, they finally got their fill and wandered off to pupate and become moths, leaving the trees to sprout new leaves and grow unhindered for the rest of the summer. The trees may grow more slowly, but their survival (and therefore the survival of the tent caterpillars that depend upon them) is not in peril. 

 

Hibiscus Sawfly and Rose Mallow Hibiscus

Near the gazebo in the Barden at Herrontown Woods grows the local native hibiscus (H. moscheutos). Earlier this summer, its leaves were getting eaten. 

Some internet research suggests that these are larvae of the hibiscus sawfly. 

If the culprit had been an introduced insect, I might have worried. For instance, each year I see more evidence of our arrowwood Viburnums being eaten by the Viburnum leaf beetle, an insect introduced from Europe. Because the beetle's arrival is fairly recent, we don't know if it poses an existential threat to Viburnums.

But given that the native hibiscus sawfly has been interacting with the native hibiscus for thousands of years, that long track record of coexistence is reassuring.

 

Though many leaves were partially eaten, the hibiscus grew new ones that remained unaffected. I think of this relationship as akin to someone who donates a percentage of their income to good causes each year. 

An Aphid-like Insect and Hickory Trees

Earlier this year, some leaves of a young hickory tree developed these green bumps. They appear to be hickory leaf galls, caused by an aphid-like insect in the genus Phylloxera. 

The hickory leaves ultimately curled up. The insect's lifecycle sounds much like that of the introduced nematode that causes beech leaf disease. Should we be worried for the future of hickories?

Again, the aphid-like Phylloxera and the hickory tree "go way back," and through those millennia a balance seems to have been struck. Only the lower portions of the tree appear affected. The hickory continues to grow. 

Psyllids and Persimmon

Lastly, a twig on a native persimmon in Herrontown Woods was showing symptoms of contorted leaves similar to those proliferating on nearby beeches. Might we be losing our persimmons? Again, some internet research points not at apocalypse but at coexistence, between the native persimmon and a native insect called the persimmon psyllid. 

According to a NC State website,

"On native persimmon, these psyllids can be temporarily abundant; but their populations soon decline naturally, as they are attacked by their natural enemies, including parasitic wasps."

For some, even small blemishes on a plant will be annoying, but in a nature preserve, the long-sustained give and take between the plant and animal worlds is part of a complex food web to be celebrated. 

We could wish that the beech and the introduced nematode that threatens it would ultimately come into a balance that allows coexistence, but other native tree species laid low--chestnut, elm, ash--remain marginalized, even, as in the case of the American chestnut, more than a century later.

Finding Pawpaws in Paw Paw, Michigan

When the Lunar Octet, a latin/jazz band I've been in for 40 years, performed this past weekend in PawPaw, MI, a jazz naturalist like me was naturally curious about whether there are any pawpaws growing there. 

The town, named after the PawPaw River, which in turn was named by the indigenous people after the pawpaw trees that grew along it, has a population of about 3500.  Though the downtown preserves some historic feel, the town has not exactly embraced its namesake. Grapes ornament the town logo on the water tower and elsewhere, not pawpaws. 

Upon arrival, I asked my phone where I might find a pawpaw in Paw Paw, and was directed to the post office, where I navigated past redbuds and callery pears before finding this pawpaw tucked around the side. 

The tree had fruit, but none ripe as yet. I asked around, at the sandwich shop and down along the beautiful lake where we performed. Most people were unfamiliar with this native tree. The post office worker I ran into said he didn't know anything about pawpaw trees in PawPaw, except that he doesn't like the taste. 

The flavor of a pawpaw, a rich, creamy combination of mango, banana and pineapple is appealing to some but not everyone. Our host was more generous with her knowledge and assessment, mentioning a couple places the pawpaw grows in town, including at one of the schools.

The town of Pawpaw sprouted along the Territorial Road, one of the three main east-west routes of pioneer days. That history is documented next to the lake, but the native tree remains largely unknown and uncelebrated in a town that bears its name. 

My theory is that, since Asimina triloba primarily grows in floodplains, the pawpaw trees were lost when the river was dammed to make Maple Lake. Its fruit, with fragile skin and a taste less universally appreciated than other tropical-tasting fruits, resisted mass marketing. That, and the general drift away from plant knowledge, consigned the pawpaw to obscurity. 

Still, it remains a singular fruit, the only member of the tropical custard apple family, Annonaceae, to adapt to northern climates. And some of us still remember the song: "Way down yonder in the pawpaw patch"--a pawpaw patch that, in PawPaw, Michigan, became a lake with a lovely breeze to carry our music. 

Update: Turns out that, if you live in PawPaw Michigan, you'd have to drive to southern Indiana or Ohio to find a festival celebrating the pawpaw. PawPaw's festival celebrates grapes.

New: Field Guide to Mushrooms in Herrontown Woods

Thanks to Peter Ihnat and his daughter Raisa for sharing their extensive knowledge of mushrooms in a Field Guide to the Wild Mushooms and Fungi of Herrontown Woods. 

Peter and Raisa return today, Sunday, August 4, to Herrontown Woods to lead a mushroom walk from 11am - 1pm. 

Raisa posts about the mushrooms she encounters on her instagram account, foragingwithraisa.