Riffing on Wetlands at Princeton High School

This is one of the merry crowds of environmental science students who came outside to hear me riff on wetlands while standing firmly planted in that wonderful mud. Princeton High School's ecolab wetland is blessed with an upscale metal fence around it to lean and learn on while gazing down at all the native plants, crayfish, and other life. While sounds of jazz drifted over from the performing arts wing, I described the ecolab's beginnings in 2006, and how being in a band had helped me learn the basics of bringing people together to make something beautiful, applicable to all community initiatives.

Inbetween classes, there was time to photograph the contrast of seedheads and leaves on a buttonbush,

and the abundant seed clusters of boneset and Joe-Pye-Weed.

Teacher Jim Smirk explained how the school's sump pump provides a consistent supply of water from the basement, kicking on every 15 minutes or so, even during droughts. Without that hydrologic stability, many of the wetland's species would die out, leaving only those plants that can withstand extremes of wet and dry.

The rich balance of native species requires periodic intervention to weed out the more aggressive types that would otherwise take over, particularly willow and cattail. There's a great crop of Hibiscus seeds (black salt-shaker-like capsules in the photo) because students pulled out cattail this spring that would otherwise have overshadowed the Hibiscus.

I explained that, without this sort of followup by people who know which plants to leave and which to pull, native plantings can become overrun by a few aggressive species, which can then lead to a decision to mow it all down and return the area to lawn. A native planting is dynamic and evolving, requiring an ongoing care relationship that goes far beyond the static "mow, blow, and go" custodial approach that gives us the tidy but monotonous urban landscape of trees and turf.

The ecolab wetland has worked out so well over the years that Mr. Smirk and his students want to collaborate with me and others to plant two additional detention basins at the school. All in all, a fun day of talking to the kids about a favorite topic.

What's Not To Like?

A native vine shows its pretty fall foliage on a snag next to the parking lot.

Radiant colors, a feast for the eye,

and berries for the birds!

What's not to like?




Hint: Leaves of three.

A Spider Seeks To Catch the Sun

One evening, when the sun was dipping low, an ambitious spider thought to itself, "What if my web could catch the sun, and I could live upon its energy for all my days?

It tried from top and tried from bottom, but the slippery sun slipped, slipped, down and away.

Another spider, across the windswept bridge, saw the moon and thought, "What if I could catch the moon in my web, and feast upon its dreams? What a beautiful life it would be."

It tried from top and tried from bottom, and thought for a moment to have captured a lifetime of wondrous moonlight. But the moon climbed higher, higher and away.

Even the moon's reflection stayed stuck upon the glassy water.

Then another spider, having to cast its net like an airborne fisherman, looking down as the lake looked back, said to all the others, "Let us leave the sun and moon to their risings and fallings, and catch instead the bugs, who catch their energy from the plants, who catch the sunlight from the sun, and we shall feast upon the sun's energy for all our days."

And so it came to be, that the spiders lived in their village stretched across the water, catching bugs and summer sunsets, and moonlit dreams, while cars sped by, seeing nothing.

Afterthought: I didn't think about it at the time, but photographing the sun, even when close to the horizon, may not be the best idea. Even if I was only looking at the sun's image in the iPhone, not the sun itself, that's some pretty intense light. Keeping my eyes flitting about, not resting the gaze, surely helped. Lots on the web about this, due to the recent eclipse. Apparently the sun isn't bad for the iPhone, especially at sunset, but I wonder about the intensity of the image on the screen, and articles especially warn against using selfie mode with the sun because of the reflection of radiation off the iPhone onto one's eyes. Fortunately, I kept the camera pointed at nature rather than self, and it seems like no damage was done.

Wanted: A Few Good Herbivores

If you encounter a book or article that claims that, surprise!, invasive species aren't such a big problem after all (a few were written over the past decade), you'll probably find no mention of herbivory. They'll say that invasive plants are being falsely maligned, because actually they do wonderful things, like provide berries and nectar for wildlife. But it's to the plant's advantage to have its flowers visited and its berries consumed. What the plant doesn't "want" is to be eaten, and therein lies the problem with plants that become invasive. For whatever reason, be it an invasive's chemical defenses or ingrained dietary habits, the wildlife tend not to eat them.

Nature depends on consumption to keep things in balance. We love nature for its beauty and variety, but behind the scenes there's a whole lot of mastication going on. Take away predators and the deer population explodes. Introduce a new plant that the wildlife won't eat, and there's potential for that species to make habitat less and less edible as it displaces the natives. To fill this void in consumption, people have had to play the role of herbivores. What we do at Herrontown Woods, as we cut down dense groves of winged euonymus and other nonnative invasive shrubs, is to play the role of the missing herbivores, using our loppers for teeth.

There's some pleasure in the work--pleasing vistas created, serendipitous discoveries. But all things being equal, it would really be nice if the resident wildlife could show some flexibility in food preferences and fill the void in consumption. Invasives, after all, represent a huge, untapped food source for any animal willing and able to broaden its palette.

Given how much work it would be for humans to play the role of herbivores in the forest, any evidence of wildlife gaining an appetite for invasive plants stirs some hopefulness.

For instance, an invasive honeysuckle shrub was recently found stripped of its leaves. A closer look revealed something had been hard at work, its mandibles outshining our loppers: the caterpillar of a snowberry clearwing moth, also known as the "hummingbird moth" or "flying lobster", for its capacity to hover in front of flowers as it sips their nectar. Maybe if we had more summer wildflowers for the adult moths to feed from, their caterpillars would help control the populations of bush honeysuckle in Princeton's preserves. Nice to think, anyway.

And what's this orange plant growing on a dense expanse of invasive mugwort that grows as a monoculture along the gas pipeline right of way in Herrontown Woods? Dodder is a parasitic plant with little capacity to gather energy from the sun. Instead, it wraps itself around other plants and sucks out their juices.

Usually, its impact is small, but this must have been a particularly good year, because a sizeable patch of mugwort was sucked dry.

If only we could get the dodder (genus Cuscate) to preferentially neutralize the mugwort all along the right of way, some diversity might return. Again, a nice thought and tall order.

A new invasive trying to gain a foothold in Princeton is mile-a-minute vine, with a distinctive triangular leaf, a prickly stem, and a growth habit to match its name. Another post shows how invasive this annual vine can be , on farms just outside of town. Fortunately, after weeding out a small population back in 2007, I know of only two patches currently growing in Princeton, still small enough to control and hopefully eliminate altogether.

One's at the Princeton Battlefield. This year's growth was pulled out in early summer, and when checked in late August, the patch had only managed to produce a few leaves, all of which were being very effectively munched on by a weevil intentionally introduced to the U.S. to bring this rampant new species under control.

Ah, I concluded, to control mile-a-minute vine, simply reduce the patch in early summer, leaving enough for the weevils to sustain their population on. Their appetites appeared to be sufficient to prevent any flowering or fruiting that could lead to the patch spreading elsewhere.

Nice concept, but it wasn't working at the other site, down along the driveway into Rogers Refuge, where the vine had sprung back up, flowered and fruited, undeterred by the minor nibblings of the weevil. That patch had to again be pulled out by hand.

Another discovery was the work of the Ailanthus webworm moth, which had completely defoliated a young tree of heaven near the parking lot of Herrontown Woods. The moth, like the tree, is an introduced species.

If you have flowers like boneset growing in your backyard, you may be helping the adult moths to prosper.

Here again, though, the larvae have thus far been seen only on very young trees, with larger ones largely left untouched.

These are glimmers of hope, sprinkled across Princeton. It will take some concerted mastication by as yet unnamed herbivores to stem the tide of rapidly spreading species like porcelainberry, callery pear and stiltgrass--a giant uneaten salad that grows by the year. A little salt and pepper, perhaps?

Hicans and Other Useful Trees at Princeton Battlefield

When people think of trees at the Battlefield, the first and perhaps only tree that comes to mind is the Mercer Oak, which these days is Mercer Oak II, an offspring of the original, donated by Louise Morse, a remarkable woman who spent much of her long life advocating for good causes. She was wife of Marston Morse, one of the first generation of mathematics faculty at the Institute for Advanced Study.

The Mercer Oak plays an ambassadorial role for the Battlefield, a star, positioned near the road while other less heralded trees serve more prosaic functions further back.

The young oak, a teenager or perhaps a young adult at this point, is flourishing after donating much of its foliage to the insect world two years ago.

It's appropriate that the oak came from Mrs. Morse, because she herself was extraordinarily long lived, reaching 105, and, like an oak that gives of its foliage to 100s of species of insects, gave generously of her time to such causes as Stuart School and civil rights.

Closer to the house are less known but more edible trees. Beneath this one is a bumper crop of pecans, but the tree is not fully a pecan tree.

It is, instead, a hican. Like a mythical beast whose body doesn't match the head, it has the base of a hickory and the top of a pecan. You can see the change in bark from rough to smooth about six feet up on the trunk.

Chinese chestnuts, too, are having a banner year.

In front of the house, a native chestnut we planted (15/16th American), is hanging in there, though its trunk is nearly girdled by the blight.

It, too, is laden with chestnuts.

Another native chestnut on the other side of Mercer Street had looked to be flourishing, but succumbed suddenly this year. The disease does not kill the root, however, so multiple sprouts rise from the base, to be browsed on by deer.

Undeterred, Bill Sachs and I added protection to some more recently planted native chestnuts that were getting beat up by the mowers. Such a perilous world these trees enter into.

Along the field edge, the bicentennial dogwoods planted in 1976 are benefitting from the work volunteers did this spring to keep the porcelainberry vines off of them.

This shot from underneath the trees shows the wave of porcelainberry that wasn't quite able to reach the lower branches of the dogwoods.

The less shading from the vines, the more berries the dogwoods can produce to fuel the fall bird migration.

This would be the fate of the dogwoods if we didn't help them out--completely enveloped by the porcelainberry.

Two of the classic inedible trees to be found around historic homes are horsechestnuts and black locust. Clark House lacks the horsechestnut but has several grand black locusts. Black locusts provided extraordinarily rot-resistant wood for fenceposts, abundant flowers for honey, and some say they help steer lightning strikes away from the house.

The Viburnum Leaf Beetle's Gathering Harm

This fall, before the leaves fall off, check any Viburnum shrubs you know and love, whether in your yard or in your favorite nature preserve. Do the leaves look like this, pitted with holes, or even stripped down to the veins?

Most people have heard by now about the Emerald Ash Borer's rapidly multiplying demolition of our ash trees. Lest that devastation not be enough ecological and horticultural tragedy to absorb, there is another invasion underway in Princeton, by the Viburnum leaf beetle. This one--a European insect that first showed up in Canada before spreading to the U.S., is going after our understory, one Viburnum species at a time.

This and the above photo are of Viburnum dentatum, the arrowwood Viburnum, which grows here and there in our woodlands, preferring wetter soils. The light damage could have been done by a native insect, or by the first few Viburnum leaf beetles to show up, suggesting much greater damage the next year. Listed as "highly susceptible" on Cornell's website, the arrowwood Viburnum will be the first to succumb.

The maple leafed viburnum, frequently encountered along the Princeton ridge, is less susceptible and thus isn't showing any damage this year. As the Viburnum leaf beetle increases in numbers and exhausts the most susceptible species through complete defoliation, it will presumably begin attacking those that are less susceptible.

We are not completely helpless as yet another careless introduction to the continent wreaks slow motion havoc. This site offers some ways to prevent the beetles and their larvae from consuming your favorite specimens. As with all environmental damage done, the ecological and aesthetic services these shrubs were providing for free will now start coming with a price tag for human maintenance.

The Cornell site offers another ray of hope. An extension official in Rochester, NY asserts that even highly susceptible species may in the long term become viable again, as predatory insects and soil nematodes build up to prey on the Viburnum leaf beetles. Then, perhaps, the introduced species would come into some sort of ecological balance, doing some damage but not enough to kill the Viburnums.

It's a perfectly logical and reassuring scenario, and yet observation often brings into question the speed and effectiveness of nature's capacity to restore balance and sustain diversity. More often, invasive species remain dominant and destructive, be they Phragmitis, or Japanese stiltgrass, or porcelainberry. I called up the Frick Park Environmental Center in Pittsburgh, where I had first witnessed the devastating impact of Viburnum leaf beetle a decade ago. Asked whether they had seen any signs of balance being restored, they answered, "Not yet."

Related links:

The Pennsylvania extension service also has some useful information.

Past NatureNotes posts about the Viburnum leaf beetle, dating back to 2013, can be found here.

This post explores the likely aftermath of the Emerald Ash Borer invasion currently underway.

Ragweed and Fall Allergies

One native plant that people suffer from allergies in late summer may be less than thrilled about is ragweed (Ambrosia artemisiifolia). Its flowers are green--there being no need to attract pollinators since it spreads its pollen by air. This solitary plant was found on Hamilton Ave, but a much larger source of all that pollen is nearby.

Gardeners sometimes get the urge to plant gardens on school grounds, but followup tends to get iffy during summer vacation. Thus, many of the 13 or so raised beds at the Princeton High School fill with weeds during the summer, and ragweed is one of the more stellar performers, acing the grab-the-sunlight test.

My younger daughter and I planted one of the beds with native wildflowers--cutleaf coneflower, New England aster, late-flowering thoroughwort--as a sort of mid-summer charging station for pollinators. These species are no shrinking violets, but even so, a late summer weeding yielded a considerable pile of ragweed, etal.

If you're lucky enough not to suffer from fall allergies, it's possible to admire the sheer exuberance of the weeds in these beds: pigweed, horseweed, foxtail, and, alas, ragweed.

Might the fall allergy sufferers in the PHS neighborhood proactively organize to weed the raised beds before the ragweed's flowers mature? Something for someone to put on their digital calendar for next year.

With Trees, Looks Can Be Deceiving

Here's a tree that looks dead, but is probably okay. It's a horse chestnut--a species long associated with historic houses, and like many horse chestnuts lost its leaves early, perhaps due to a leaf blotch fungus. Though planted in front of a newer home, its history is connected to the 18th century house around the corner, once lived in by Joseph Stockton and, reportedly, an occasional sleeping pad for Thomas Jefferson.

And here's a recently planted ash tree a few blocks away at the Westminster parking lot, looking good but not long for the world, due to Princeton's ongoing Emerald Ash Borer invasion. When I saw that ash trees were planted as part of the parking lot expansion, I urged Westminster to get the designers to pay for replacements that would actually live long enough to shade the cars parked beneath them. Hoping I'm wrong about it all, but any followup photo a few years from now will likely show a gap where this tree now stands.

September Captured in Bouquets

Bouquets from the backyard can be a good way to learn the names of plants. The two visible here are cupplant on the left, ironweed on the right.

This one shows off purple coneflower, boneset, Indian grass, a species of sunflower, turtlehead, and clusters of stonecrop--a nonnative sedum that turns color as fall progresses, from green to pink, to burgundy to rich brown.