Seeking "Lingering Trees"--Some Hope for Ash and Beech Trees

Most people attentive to nature are aware that Princeton has lost nearly all of its native ash trees over the past decade, and is now poised to lose its native beech trees as well. These are only the most recent losses due to assorted introduced insects, nematodes, and diseases against which our native trees had not evolved resistance. Also gone from the canopy over the past century are American chestnuts and American elms, with bacterial leaf scorch also taking a toll on red and pin oaks. As additional organisms enter the country due to an appalling lack of biosecurity, other species are threatened. 

What is there to do other than mourn, and mourn again, with each new wave of devastation? 

One answer to that question may be: Keep an eye out for "lingering" trees. It would be easy to assume that all our native ash, not having co-evolved with the Emerald ash borer (EAB), would be equally defenseless as the introduced larvae eat through the cambrium, cutting off the tree's circulatory system. But an initiative in Ohio has shown this not to be entirely true. Jennifer Koch, a research biologist with the USDA Forest Service, has been leading an effort to find "lingering ash", that is, mature ash that survive while others all around them succumb. Some ash that she and others have found have natural defenses that kill 20-45% of the larvae that bore into them. A very few trees kill 100% of the invading larvae. 

A very watchable video features Jennifer Koch, and also Holden Arboretum's Rachel Kappler, telling the 
story of ash lost, lingering ash found, and the effort to increase resistance among lingering ash through research and breeding programs.

One particularly impressive slide in the presentation showed how the resistant trees are able to stop the invading larvae before they do damage to the tree. 

 
Here are some of my notes from the video:

• Ash wood is/was used for bats and guitars
• Native ash species in our area: White, green, black, pumpkin
• 300 million acres of black ash-dominated forest in Minnesota could be lost (apparently no other tree species can survive in those wet areas)
• green ash is an important riparian buffer species in the plains states, hard to replace
• The lingering ash are found individually or in clusters, e.g Swan Creek, Oak Openings Park, near Toledo, 108 out of 11,000 had healthy canopies. Two specimens had no evidence of attack. Most resistance is partial, but resistance can be increased through breeding
• greenhouse tests can reduce the amount of land/labor needed for field tests
• resistance is inherited, though uneven

A central point these researchers make is how very limited is the area they have surveyed for lingering ash--only a small area near the Ohio/Michigan border. They call for similar initiatives in other parts of country. 

That's where we come in, as keen or at least intermittently keen observers of the landscape through which we walk. It's important that any tree we believe to be lingering be a mature, wild tree--not a cultivar in a planted landscape--and that it be a tree that has weathered the massive wave of EAB over the past ten years, remaining green while others nearby have succumbed. Photos of lingering ash, and one story of their discovery, can be found at this link. 

A brief mention of the various species of ash: I associate white ash with higher ground and grander specimens found or once found around town. Green ash are less statuesque and more associated with wetter ground. Black ash I think of as growing, or having grown, in swamps, such as at Rogers Refuge in Princeton. The Ohio initiative is apparently finding most success with resistant green ash, though the video mentions lingering white, green, and black ash having been found in NY state.

In addition to the info below, there's also anecdata.org--a platform where citizen scientists can set up reporting initiatives.

This keeping an eye out for "lingering" ash can also be applied to other imperiled species in our area. The Ohio researchers request that people report lingering American beech, hemlock, and American elm as well. 

Related posts:

Emerald Ash Borer in Princeton

Beech Leaf Disease Sweeps Across Princeton

Holden Arboretum Studies Resistant Beech and Ash Trees

An Homage to Princeton Ecologist Henry Horn

This homage to ecology professor Henry Horn was written after the very moving memorial service for him in the Princeton Chapel nearly six years ago, and has just been rediscovered, sitting patiently in the draft folder.

Though March 14 is memorable as Einstein's birthday, I'll remember it too as the day we lost Henry Horn, the beloved Princeton professor and naturalist whose many-layered ways of studying the natural world and communicating it to his colleagues and the larger community made him unique in all the world.

I knew him primarily from nature walks--those he led in various Princeton preserves and those of mine at Herrontown Woods that he would show up for and add so much to, often with his wife and botanist, Betty. On these occasions, his sonorous voice would convey warmth and clarity as he shared his deep knowledge of geology and forest ecology.

At the May 5 memorial service under the vaulted, ornate canopy of Princeton University Chapel, a colleague called Henry "the heart of the Department of Ecology and Evolutionary Biology." For me, he occupied a similar place in the community. Talking to him, I felt no sense that I was on the other side of a wall that some professors construct between themselves and the outside world. I found in Henry Horn no sense of division or Other, no Nassau Street of the mind dividing ivy league from community.

After the service, I mentioned this to one of his younger brothers, and asked how this combining of academic achievement and commonality had come to be. He said that, though later Henry would go to Harvard, their parents had insisted that their children attend public schools, where they were around people of all walks of life. Henry's mother had had a hard life growing up, and there was always something to restore humility when their heads got too big.

At the service, we learned that Henry's father had been a minister, whose various positions had taken the family from Virginia to Georgia for four years before moving north to Boston. I asked him (the younger brother) if the family's southern roots might have something to do with Henry's easy connection with people outside academia. I explained that I had lived in North Carolina for eight years, and had felt in many ways like I had found home. It was the habit of people there to consistently acknowledge the existence, the humanity, of others. Known or stranger, it made no difference. He immediately knew what I was talking about, and said this aspect of the south is not sufficiently appreciated in the north, where people tend to stereotype southern sensibility in negative terms. 

While many scientists studying nature conduct their research in distant locales, Henry found value and meaning in local woods and fields. He was quoted at the service as saying, "You don't need to travel far away to study nature". His treasuring of the local could be considered prescient, given the university's recent efforts to connect more with the community.

Henry was one of the older among nine or so siblings, in a house they filled with the collected gleanings of nature. Most were brothers, but the oldest was a sister who would return from school and share with the others everything she had learned that day. That sharing was described as a university education in and of itself.

Most of us who knew Henry a little or a lot knew him as warm, insightful, infinitely curious about the world, whimsical. It was a surprise, then, to find out that he had a competitive side, and had an inner toughness, as when he stoically endured the brutal welcome dished out by a gang of boys when his family first moved to a neighborhood in Boston. He and his brothers ultimately gained the new neighbors' respect and became friends with some.

As a kid, he had a passion for tinkering with watches and electronic devices, taking them apart and putting them back together again. This tinkering led during his years as an assistant professor to what he would later call his "tenure machine," a device for assessing forest canopy and shade tolerance that led to an influential book that in turn led to his gaining tenure.

His scientific inquiries seem frequently to have led to art, and vice versa. As can be seen in a wonderful video portrait of Henry, entitled Boy Wonder Emeritus, he got ideas for art from the patterns he saw in his photos of canopy, and the carved wooden animals he would pull out of his pocket to use for scale in his nature photography served as ambassadors to help convey science to youth.

He was a force for cohesion on campus, providing advice and constructive feedback to all who sought him out. Resisting the academic temptation to withdraw into this or that silo of specialized study, he showed up for a wide range of talks. He also somehow avoided the human tendency to focus questions or comments on perceived flaws or gaps in a presentation. He instead would ask supportive questions that suggested new avenues of inquiry, and sometimes would even help clarify for a less than articulate speaker what he or she had been trying to say. His aim was to bring out the best in others, not tear them down.

As Samuel Barber's Adagio for Strings filled the chapel, above and all around and in our hearts, I wondered if Henry Horn's passing represented also the passing of an era when the work of biologists took them outdoors, rather than into a lab. A colleague of his assured me that much research in the EEB department still takes professors out to the field. 

Thinking of that era, I remembered my own mentor, Herb Wagner at the University of Michigan, 20 years Henry's senior. It was the 1970s, botany classes were overflowing, environmental legislation had bipartisan support. Wagner's office was filled with specimens of plants and butterflies, gathered from near or far. Classical music on the local public radio station would waft out into the hallway, interrupted only by a few minutes of news at the hour. We were still innocent of any awareness of climate change, and populations of invasive species and deer had yet to explode. Distrust of government and scientists had yet to be injected deep into the national psyche.

Having learned about Oswald Veblen, the renowned mathematician and conservationist who preceded Henry Horn at Princeton by sixty years, I can't help but see Henry as Veblenesque in many ways. Both reached beyond academia to connect with the community. Both were deeply drawn to the land. It was Veblen who worked to acquire the land that later became Henry's beloved Institute Woods. Both worked hard to support and advance others' careers. And when they faced physical challenges--for Veblen it was partial blindness, for Henry it was a handicapped child--their response was to invent devices that would help not only in their own situations but for others facing similar challenges.

The Princeton University obituary for Henry serves as a good continuation and elaboration upon what I offer here. A couple quotes:

In 1991, he led the University into a new era of interdisciplinary environmental research as founding director of the Program in Environmental Studies. He transferred to emeritus status in 2011.

“He had an original mind and was so caring. He saw patterns in the natural world that others often overlooked"

Henry lives on in many ways, including some online videos:

Henry's nature walks
https://www.princeton.edu/news/2018/07/16/nature-walks-henry-horn

Skunk Cabbage
https://vimeo.com/278156799

Mockingbird
https://www.facebook.com/watch/?v=632608590467273

Comments on Henry in memorium
https://blogs.princeton.edu/memorial/2019/03/henry-horn/

Touring a New Preserve in Plainsboro--Bulk Farm Nature Center

My friend James Degnen called me up recently, and with his deep baritone voice invited me to explore the Bulk Farm Nature Center--a new nature preserve in Plainsboro, NJ. A former tree nursery, the preserve has cherry blossoms in the spring, leaf color in the fall, and lovely vistas through the winter. Note: The back portion of the preserve, with trails that reach the Millstone River and a bald eagle nest high in a tree, is closed from January through July, to avoid the bald eagles' nesting activity. 

Acquired in 2008, the property took fifteen years to prepare for public use, opening in September, 2023. Some soil contamination was found, likely requiring a lengthy bureaucratic process of remediation.

Though the 80 acre preserve is easily accessed at 179 Cranbury Neck Road, you'll need to navigate past the unusual name. It's called a Nature Center, but there's no building, and "Bulk" refers not to any particular aspect of the preserve, but instead to the family that once owned the farm. Like those housing developments that are named after whatever natural feature was destroyed during the course of development, this nature preserve may ironically be named after a building demolished after the land was preserved. Similarly, the gravel road bisecting the property is called Homestead Drive, leading presumably to a homestead that no longer exists.

A trail map is available online. 

James explained that the soft gravel of the Homestead Drive is to be avoided in favor of the mowed trails winding back along either side. 

Though lacking any topography, the preserve's trails take you through a varied landscape with broad vistas across meadows. At first, the meadows are solid with goldenrod, but deeper in some of the native grasses--broomsedge (as in "Andropogon Trail") and purple top--become more prevalent. 

The map conveniently marks where benches can be found, built to last well into the next century. 

The groves of nursery trees prove yet again that it's easier to plant a tree than to sell it.

Most trees are small, but somewhere towards the back right of the trail system we encountered an extraordinarily large river birch.

Towards the back of the preserve, you reach a gate that will be closed and locked for the first seven months of the new year. Bald eagles nest in a tree near the river, and are not to be disturbed. 

It not being January yet, we were able to hike all the way to the back of the preserve, and see the very impressive eagle nest. The tree appears to be a red oak fighting a bad case of bacterial leaf scorch. 

Beyond the eagles' nest, the trail ends at a tranquil spot along the Millstone River. James said the water continued to flow through the long drought this fall.

On the way back, James partook of a pet pleasure--releasing milkweed seeds to the wind.

One curious plant you may encounter in the expansive meadows is this shrub with red stems. Though multiflora rose is a highly aggressive, thorny invader of our natural areas, it is sometimes slowed down by a disease that spread to NJ from the midwest. Called rose rosette disease, the disease stunts the leaves of the multiflora rose and turns the stems red, particularly in sunny locations. 

A gray birch's bark doesn't flake like the bark of a white birch. Both of these birch species are native further north.

The hike took about an hour. Thanks to James for making me aware of this new preserve a fifteen minute drive from Princeton. James' rich baritone voice, by the way, is in demand for doing voice-overs, and we collaborated back in 2019 on a film project in which we recast The King's Speech as a call for action on climate change. 

Past adventures up Plainsboro way:

The Plainsboro Preserve is Anything But Plain

Kayaking Up the Mighty Millstone Marsh

And another tree nursery turned nature preserve, in Lawrence Township: 

The Lost Meadows of Maidenhead Meadows

Whither the Migration of Monarch Butterflies?

Though the number of butterflies in general was radically down this summer, I still saw the occasional monarch. Some appeared frantic. Were they searching in vain for a mate? Other times they'd pause on a flower to take a long drink of nectar. Sometimes I'd just see a flash of orange out of the corner of my eye. No other butterfly can match a monarch's nimble power in flight. The number of sightings, maybe ten in all, wasn't much changed from previous years.

Their longterm prospects, though, are very much in question. Chip Taylor, who has tracked migrations as closely and for as long as anyone, says that monarchs as a species will survive, but their fabulous migration will not. Last year's overwintering numbers on Oyamel fir trees in the mountains of Mexico was the second lowest ever recorded. Resilient as the monarchs are, it's hard to imagine the delicate dynamic of migration surviving the rapidly increasing disruptions of climate change.

Yes, climate has changed in the past. It's said that, before humans started altering the atmosphere, the earth experienced a progression of ice ages every 100,000 years or so. During the last ice age, glaciers extended south almost to what is now NY City. What we have now is change at a speed far beyond the capacity of species to adapt, as our machines pour a massive overdose of carbon dioxide into the atmosphere.

In a blog entry this past August, Taylor explained how extremes of weather can affect the monarchs' capacity to build numbers over the summer and migrate back to Mexico in the fall. Extended heavy rains in early summer can delay egg laying. Warmer temperatures in September and drought in October can impede a fall migration historically aided by cool winds out of the north. What we got this year was hot and dry, with three months of drought and warm weather extending into mid-November. That's a radical departure from anything I've ever witnessed.

Each year towards the end of October, I start looking for news about the migration south to Mexico. The first headline I found confirmed my suspicions: "This fall's monarch butterfly migration through Texas doesn't look promising." Then, finally, a report on-site at the roosting grounds in Mexico. Though a few had been straggling in over the past few weeks, the first largish group of 2000 monarchs wasn't reported until Nov. 21. In past years, monarchs would predictably arrive en masse in the first week of November. Then, after the monarchs had settled into their roosts, the Biosphere Reserve would be opened to tourists mid-month. This year that opening was cancelled, stranding those tourists who had traveled far to witness a unique example of nature's splendor. This is not the only destination being compromised in a world being heated in part by global tourism. There are different ways to show love for nature. Touristic love, which I was a part of in the past, becomes more ironic by the minute.

The radically dry, warm weather we've experience this fall has a lot to do with the increasing instability of the jet stream--high winds out of the west that normally feed us a steady stream of contrasting weather, but can get blocked and diverted north or south, causing weather systems to linger indefinitely. The jet stream is driven by the difference in temperature between the tropics and the arctic. As the arctic heats more quickly than lower latitudes, the temperature gradient is reduced and the jet stream becomes more malleable. 

Consider the extraordinary ambition and brilliance of the monarch butterfly's eastern migration. Huddled overwinter in the mountains of Mexico, its numbers head north in March, then each succeeding generation--usually four total--fans out from Texas to harvest the richness of flowers and milkweed foliage from the whole eastern half of the U.S. and even up into Canada, before somehow knowing how to navigate all of that embodied richness back to their little hideout in Mexico. Over the past million years, the distance flown would have contracted during ice ages, then expanded as the glaciers withdrew. I think of the monarch migration as akin to a rubber band, stretched northward by the supply of nectar and milkweed, then contracting back down to Mexico for the winter.

The vast territorial expansion each summer is surely dependent on numbers. Otherwise, how will the monarchs find each other to mate as they spread out across the continent? Though much different in behavior, the passenger pigeon was also dependent on big numbers. Its demise, more than a century ago, was due to radical habitat change and a wanton harvest and slaughter that Aldo Leopold described as "trigger-itch." Now, our itch is to take photos, and our intention is to preserve. And yet, we watch as the collateral damage of a machine-driven economy accumulates.

A post on the Monarch Watch Blog describes the Symbolic Monarch Migration that school kids in Mexico, the U.S., and Canada take part in. Kids in Mexico send paper monarchs to kids up north in the spring, and vice versa in the fall. Monarchs ignore country boundaries. They are telling anyone who takes time to listen that our interests don't stop at the border, what we do affects people and nature far away. 

One halcyon autumn day when I was a kid, walking across the broad lawns surrounding Yerkes Observatory in Wisconsin, I was astonished by the sight of countless thousands of monarchs flying above me. There was a thrilling collective energy to their flight, not dutifully unidirectional towards the south but instead more like a dance. They seemed to feed off of each other's proximity and energy--an uncanny mix of whimsy, skill, and determination. 

If the great migration were to be lost, monarchs would still persist in pockets further south, but they wouldn't be the same monarchs we've known and loved. Here's a post on how the loss of migration's rigors would change them.

Still Here--A Late Fall Walk in a Desiccated Forest

On a Sunday morning in November, sipping coffee and socializing at May's Cafe in the Botanical Art Garden, 

a couple of us got to thinking: "Wouldn't it be a nice day for a nature walk in Herrontown Woods?" 

As we thought upon that thought, other thoughts sought to intrude. We are a merry crew--by habit, it would seem--finding some buoyancy even as beneath the usual merriment there has grown a deepening trepidation. The world is being rocked by disruption--politically, biologically, climatologically. These November days are discomfortingly comfortable, the woods are bone dry, the trees aching from drought. What will spring be like after a fall like this? In a world where disruption reaches into every nook and cranny, the very concept of refuge is under siege. We thought and thought, and thought some more until the answer finally came. Yes, we decided, a walk in the woods might be just what we need.

And so we set off, leaves crisp beneath our feet, down the red trail, then followed the silent cascade along the yellow. What to talk about? Beech leaf disease? Oh dear. I spoke of the color-coded forest--that special time in the fall when colors change and each species of tree and shrub announces itself with its distinctive color. Gaze around and grasp all at once from the reds and yellows, burgundies and browns, the species that inhabit that valley. Many of the colors were made pale by drought. Some trees and shrubs had simply dropped their shriveled leaves, short circuiting the color change, but still some colors showed. 

At the second stream crossing, it occurred to me: there might actually be flowers in this desiccated forest, in the middle of November. Native witch hazel blooms in late fall, unlike asian varieties that bloom in early spring. And yes, just off the trail, there it was, not just a sprig here and there, but a whole grove of witch hazel, massed larger than I'd ever seen or noticed, holding their countless flowers high.

One in our group, Jill Weiner, took this closeup of the curiously shaped and curiously timed blooms.

We hiked up to the cliff, to gaze out across the valley and scrutinize some interesting leaves. A white oak leaf had tiny holes--a sign of one of the hundreds of insect species that find sustenance in native oaks.

Looking out from the cliff, I saw a bright splotch of yellow, and headed down to have a look. It was a tree, though not much larger than a shrub. By the leaf shape and size, it appeared to be an American elm, a species whose grandeur I had witnessed in my youth, before it was laid low by an introduced disease. "Still here," it seemed to say. After all this, and all that, still here.

Cliff photo by Jill Weiner.

Native Fall Color and Berries in Herrontown Woods

One vision being gradually realized at Herrontown Woods through the power of incrementalism is the transformation of the long boardwalk into a native plant corridor that will be especially attractive in spring and fall. The boardwalk, given the V-ful nickname of Voulevarde because it was built by chainsaw virtuoso Victorino and leads from the main parking lot up to Veblen House, was intentionally routed past some mature examples of native shrubs.

Arrowwood Viburnum has toothed leaves (thus the latin name Viburnum dentatum) and can turn a brilliant reddish color in fall. 

We're managing the corridor for an open woodland, so that enough sunlight can reach the understory to power abundant berry making by the native shrubs. The many Blackhaw Viburnums, named after their black berries ("haw" means berry, as in hawthorn), are a dramatic example. 

The preserve's largest winterberry shrub--a holly called Ilex verticillata--greets you along a bend in the Voulevarde with abundant red berries this time of year.  

One of the preserve's large highbush blueberry bushes--they tend to be loners persisting here and there in the preserve--also grows along the route, with bright orange fall color.

The largest native swamp rose (Rosa palustris) in the preserve is also near the trail, its single pink flowers emanating a heavenly fragrance on hot summer days. Its rose hips are bigger than those of the nonnative multiflora rose. While the invasive multiflora rose is ubiquitous in the preserve, there are only two native swamp roses found thus far across 150 acres, mostly because the swamp rose needs more consistently wet conditions to compete. We've started planting more of them, in wet spots that get some sun, to see if we can increase their numbers over time. Again, the battle cry: "Incrementalism!"

Beyond the boardwalk, up towards Veblen House, is a good example of a rare native shrub, variously called Hearts a' Bustin' or strawberry bush. The deer love it so much that we needed to cage it until it was tall enough to escape their browsing. Located in a partial forest clearing, it receives enough sun to develop abundant berries.

In the fall, its leaves turn white. Hearts a' Bustin' is a native euonymus (Euonymus americanus), rarely seen due to deer browsing, while the nonnative euonymus, burning bush, is ubiquitous in the preserve and largely shunned by the deer. Notice a recurring story?

Up at the horserun near Veblen House, these look like shrubs or small trees, their fall color backlit by late afternoon sun. They are in fact trumpet vines growing on some sort of structure placed there decades ago. 

A different angle shows the trumpet vine with the bright red of Virginia creeper in the foreground. Both are native vines that can be a little aggressive, but sufficient shade deprives them of the energy to be obnoxious, allowing us to enjoy their best traits without any need to keep them in line.

Virginia creeper has five leaflets to poison ivy's three. These leaves look like they've donated some of themselves to the insect world. 

The boulders in Herrontown Woods, bedecked by mosses and lichens, are reminiscent of whales whose gray skin has collected barnacles. Sweetgum leaves are particularly creative and varied with their fall color.

Also generous with fall color is the native winged sumac, which has started to pop up in areas where we remove invasives. They seem to be part of the soil's memory of past eras when the forest was younger, before the canopy closed and shrouded the ground in deep shade. 

Another source of beauty, noticed while removing dead ash trees near the Veblen House driveway, is the combination of the old evergreen cedar trees with the deep burgundy of young white oaks rising to ultimately fill the space left by the ash.

The loss of ash trees to the emerald ash borer is a profound tragedy, but if we can take advantage of the new openings in the canopy to reawaken a diversity of native shrubs and trees, there is at least some recompense. 

Stiltgrass Reaches Michigan

During four weeks of touring with our latin/jazz group Lunar Octet in California and Michigan this summer, this "jazz naturalist" kept encountering different variations on the problem of invasive species. In the Bay area of California, highly combustible introduced grasses dominate hillsides, threatening homes. A side trip to Cleveland took me close to where beech leaf disease was first identified 12 years ago. 

And then, housesitting for my friend Sam in Ann Arbor--our home base for various Michigan gigs--I was astonished to find Japanese stiltgrass growing in his garden. Now, the only thing that would be astonishing about stiltgrass in a New Jersey garden would be its absence. Stiltgrass has become nearly ubiquitous in Princeton--coating roadsides, establishing broad monocultural meadows in our woodlands, smothering our gardens with its stilt-like growth. An annual that spreads rapidly for lack of any wildlife that find it palatable, it dies back in the fall, leaving a frozen ocean of brown in the forest, and billions of seeds to sprout the next spring. 

Stiltgrass is Not Yet Everywhere

That ubiquity makes it hard to believe that there are still many parts of the U.S. where stiltgrass has yet to spread. Until recently, though, Michigan was one of them. For a New Jersey gardener, traveling to Ann Arbor used to be like stepping thirty years back in time to a stiltgrass-free landscape. 

My fantasy, upon discovering this uber-invasive in Sam's yard, was that I had through uncanny serendipity happened upon the first colony of the plant in the area, and at a time of year when it could be pulled before it went to seed. What finer gift could a housesitter give to a homeowner and his neighbors than to nip an invasion of stiltgrass in the bud? This jazz cat was going to put a botanical bully back in the bag. 

The Horse, the Cat, the Barn and the Bag

But no. The stiltgrass--which I'm guessing first arrived as a hitch-hiker in topsoil or a nursery plant, or perhaps in the soil of a well-intended gift plant dug from some well-meaning friend's garden--had already spread far down the hillside towards the Huron River. 

Turned out Sam already knew about stiltgrass. Ann Arborites are a plant-savvy bunch. Their city already had a Natural Lands Manager, Dave Borneman, long before I moved away in 1995. Princeton hired its first Open Space Manager in 2021. Most towns and cities don't even have one.

I contacted Dave, who now has his own habitat restoration business doing prescribed burns, to ask about the status of stiltgrass in Ann Arbor. He didn't say the cat was out of the bag, but he did say the horse had left the barn. "Sadly, the horse has left the barn on this species locally. We’re seeing it pop up fairly widely now in eastern Scio and western/northern AA."

The first occurrence of stiltgrass was in fact reported seven years ago, on Sept 1, 2017, in an announcement by the state Dept. of Natural Resources. A collaboration between the DNR and a nonprofit called The Stewardship Network sought to identify and knock out the initial population, said to have been limited to one property, but to no avail. 

The First Sighting in Wisconsin 

Wisconsin's situation sounds more hopeful, with only one known infestation that is allegedly being managed and kept to a limited area. A botanist visiting from Minnesota made the early identification. Somewhat less reassuring is a post by the Invasive Plant Association of Wisconsin (IPAW), that mentions my childhood landscape in the Lake Geneva area specifically as a place where people should be "on high alert" for stiltgrass. That would suggest its been reported there.

Is Stiltgrass Controllable?

It got me thinking about what can a town do about a new invasion? Once the cat has left the barn and the horse is out of the bag, is there anything to be done? Ann Arbor certainly needs no advice from afar. Its Wild Ones chapter has an excellent fact sheet on stiltgrass in Michigan, including a field guide with details to help with distinguishing stiltgrass from some similar-looking native grasses like whitegrass. Other groups like the Legacy Land Conservancy are also engaged, sounding the warning that Michigan gardeners and land stewards now face a challenge like no other.

“Stiltgrass is not like other invasives we have seen in Michigan, which spread relatively slowly and can be contained. Stiltgrass travels via water and deer, as easily as water itself."

But Princeton's experience with uber-invasives like stiltgrass and lesser celandine can be instructive. One can say these rapidly spreading nonnative species are ubiquitous, and yet there are locales--backyards, neighborhoods, upper valleys, hillsides--within the town where one or another invasive has yet to spread. In the preserves I have managed, I have had considerable success with proactive action to keep various areas free of the lesser celandine, garlic mustard, and porcelainberry that plague other areas of Princeton. 

Much can be done to slow the expansion of stiltgrass, by patrolling in late summer, particularly along the edges of trails. Even though stiltgrass has been in Princeton for many decades, it's still possible to walk through portions of preserves and see none, or to find just a few along the trail that can easily be plucked up before they go to seed in September.

One has to keep at it year after year, catch any invasion early, and be strategic in one's timing to maximize result and minimize effort. For larger patches that would be impossible to pull, late season mowing and/or application of very dilute herbicide prevents production of new seed. Doing this thoroughly and year after year ultimately exhausts the seedbank. Scroll down at this link for more information on these approaches. 

Patrolling for stiltgrass in a preserve can even be a good motivation to get out into areas you might not frequent otherwise, and do some botanizing. It's a chance to sharpen the eye, as one distinguishes between stiltgrass and the native whitegrass, and a few other plant species with similar appearance.

The top half of this photo is native perennial whitegrass. The bottom half is the invasive, annual stiltgrass. The latter is easy to pull. The former resists, because of its greater investment in roots.

In this list of lookalikes taken from the internet, the whitegrass and the northern shorthusk have been enjoyable for this plant geek to get to know a little better this year. As is typical of native species, they are fairly common in less historically altered preserves, but don't take over like stiltgrass tends to. 

Smartweeds (Polygonum spp.), with tiny, white to pink flowers on a short spike and a tell-tale dark blotch near the center of each leaf.
Whitegrass (Leersia virginica), which is well-rooted in the soil and has longer, thinner leaves than stiltgrass, with no mid-rib stripe.
Northern shorthusk (Brachyelytrum aristosum), with fine hairs on the top, bottom and edges of its leaves and stems, and leaf veins in a pattern resembling an irregular brick wall.

That's the upside of intervening in a situation where many feel frustration and helplessness. Intervention to stem the advance of hyper-aggressive plant species gets us outdoors, often prompting new discoveries and providing a chance to gain more familiarity with the native diversity we seek to protect.

Botanizing With Seek at Indiana Dunes National Park

Things were going our way as we pulled into Indiana Dunes National Park. Swinging around the south side of the Great Lake on our way to Michigan from Chicago, we decided Indiana Dunes would be a good spot to see the shoreline. The cheerful attendant at the gate offered different options for admission. One was a $20 yearlong pass to all national parks for a senior like me. Now, that's a major perk for what still seems pretty modest longevity. 

A visit to the Chicago area offers a chance to see some wonderful restorations of the region's native habitats--prairies, oak savannas, wetlands, dunes--achieved over decades, in part through a consortium known as Chicago Wilderness. Bur oak savannas had disappeared altogether under a sea of nonnative buckthorn, and had to be recreated through botanical research, invasive plant removal, and the reintroduction of fire. 

It was surprising to learn that the Indiana Dunes, a product of receding glaciers and fluctuating lake levels that exposed sandy beaches to the wind, is the fifth most biodiverse national park, and is called the "Birthplace of Ecology." In 1986 Professor Henry Cowles of the newly formed University of Chicago started bringing his students to the dunes to study how a plant community develops over time. The dynamic dune landscape provided a gradient of stability ideal for studying plant succession, from the raw windblown sand of the lakeshore to the complex diversity of species growing on the older, more stable dunes further inland.   

Many of the dunes were mined and carted away long ago for sand. That any survive is a long story, told on wikipedia, featuring Chicago botanists and conservationists like Henry Cowles and Jens Jenson. Some credit for preservation is also due to a woman who in 1915 abandoned city life in favor of a shack on the dunes. Drawn to the spiritual power of the landscape, Alice Mabel Gray became known as "Diana of the Dunes", and advocated for their preservation. She's featured on the interpretive signage in the park.

"Her unusual, free-spirited lifestyle fascinated local townspeople and newspaper readers here and across the country, bringing national attention to the Indiana Dunes at a critical time of early conservation efforts."

Alice Gray's story triggers memories of Thoreau, and a character who lived on the beach in one of Steinbeck's novels--Cannery Row or Sweet Thursday. Thoreau spent two years at Walden Pond; Gray lived on the dunes for nine. 

For me, it was a chance to botanize. The pleasure of learning plants--their names, their shapes--is that you'll encounter the familiar no matter where you go. If you've gained some familiarity with the plant world, you'll find a lot of New Jersey in Indiana, and vice versa.

Look! There are the three shapes a sassafras leaf can make,

and the scalloped leaves of witch hazel. 

And for those plants I didn't readily recognize, I had an ambassador in my pocket, ready to provide an introduction. The phone app I use is called SEEK--a popularized version of iNaturalist. The fun thing about it is that you can point your phone's camera at a plant and the plant's name will appear on the screen. No need to take a photo. It's as if an ID label were hung conveniently on nearly every plant you pass by. 

This shrub, with its three leaflets and distinctive seedpod, reminded me of bladdernut (Staphylea trifolia)--a large native shrub that grows in only a few locations in Princeton's nature preserves. SEEK--my "pocket botanist"--called this dune plant Common Hoptree, Ptelea trifoliata. Turns out that bladdernut and common hoptree are related, being in the same Order: Sapindales.

The pine trees perched on the dunes looked familiar, with their short, paired needles. SEEK, with infinite patience, reminded me: Jack pine. I read about them fifty years ago when first discovering the elegance of fire ecology. Jack pines have serotinous cones that only open when heated by a fire sweeping through. The seeds then fall on the mineral soil ever so conveniently left exposed and fertilized by the flames--yet another clever adaptation of plants to periodic fire. In the midwest, and even in New Jersey, the reintroduction of fire into the landscape, in the form of controlled burns, has been an important element in the restoration of habitats like prairies and oak savannas.

SEEK reassured me that this was in fact winged sumac, just like the winged sumacs that have been spontaneously popping up as we restore the habitat in the Barden at Herrontown Woods. Maybe not "just like." The characteristics of a species can vary across its range, like accents in speech. 

There's a whole long list of invasive species that supposedly grow on the Indiana Dunes, but I didn't see any. What a great feeling to visit a habitat where native plants are thriving. The one weed I saw was the native horseweed. It can cover whole farm fields, but here one was growing all by its lonesome, as if on display, in a crack in the concrete. 

Another bit of luck: a threat of rain had kept the crowds away, making us one of the few witnesses to a beautiful beach and highly swimmable Lake Michigan water. Having arrived with no expectations, the beauty and a cool swim sustained us through the rest of a day of travel.

A few observations collected on the SEEK app:

Common Hoptree, Ptelea trifoliata

Tall boneset, Eupatorium altissimum

Shining (winged) sumac. Rhus copallinum

Flowering spurge, Euphorbia corollata

False boneset, Brikellia eupatoriodes