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 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. 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.

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

Native Plants Prosper in a Wet Meadow at Smoyer Park

A little video tour of a wet meadow habitat in Smoyer Park, Princeton, where lots of native wildflowers were planted and early intervention has kept invasive species from taking over. Part of my work at Herrontown Woods. 

 

 

The town helps out by mowing this basin once a year in late winter, and its deer culling program reduces the browsing pressure on the native plants so that many can bloom. This year, 2024, the basin was accidentally mowed in early June. Though traumatic at the time, the plants grew back, and the effect was to concentrate blooms later in the season. 

The detention basin was converted in 2016 from turf to native grasses and wildflowers by Partners for Fish and Wildlife. Ongoing followup by Friends of Herrontown Woods has added additional native species and prevented invasive species like mugwort, Sericea lespedeza, crown vetch and Canada thistle from taking over. Other aggressive plants that need to be countered are giant foxtail, stiltgrass, carpgrass, nut sedge, wineberry, blackberry, and pilewort. Native species being encouraged are big bluestem, Indian grass, various sedges, rose mallow hibiscus, ironweed, blue vervain, partridge pea, black-eyed susan, late flowering thoroughwort, boneset, monkey flower, buttonbush, and some goldenrods.

Herrontown Woods Nature Walk -- This Sunday, Sept. 8, 11-1

Update: We had a good walk on a glorious day. About 20 people participated, despite the short notice. The most memorable find was a brightly colored edible mushroom called Chicken of the Woods. A friend who eats wild mushrooms was nearby, and while we continued our walk, she went back to harvest the mushrooms. 

Two days later, we were invited over for a meal of wild mushrooms on pasta. She sauteed the softest portions of the mushrooms with onion and garlic. 

____________________________________

I will lead a nature walk this Sunday, Sept. 8, from 11-1 at Herrontown Woods. Meet at the Botanical Art Garden (the "Barden"), next to the main parking lot, 600 Snowden Lane in Princeton. 

Come early for coffee and baked treats at our monthly May's Cafe, 9-11. 

Great Lobelia is one of many native wildflowers currently blooming in the forest clearing known as the Barden. 

Holden Arboretum Studies Resistant Beech and Ash Trees

Herein lies a post about the long, patient work that begins when something goes wrong with the world. With the introduction of beech leaf disease into North America, things have gone very wrong. Another noble, native tree species, towering and strong, is proving no match for a microscopic nematode. When this happens--yet another example of collateral damage from international trade--scientists mobilize to seek understanding and possible remedies.

In recent blog posts about beech leaf disease, I've mentioned Holden Arboretum. Holden happens to be located east of Cleveland, close to where the disease was first noticed back in 2012. Visiting family in Cleveland this summer during a band tour, I reached out to Holden staff to see if I could stop by to witness their research on the disease. 

Tucked behind some 3000 acres of gardens and ponds, forests and fields, is a research station where Holden is devoting staff and greenhouses to a collaboration with the U.S. Forest Service and others to test resistance not only beech leaf disease, but also to the introduced insects that have decimated two other native trees--ash and hemlock. 

I learned primarily about their research on beech and ash trees.

AMERICAN BEECH

Where did the nematode that causes beech leaf disease come from? According to Rachel Kappler, Holden's Forest Health Collaborative Coordinator, who generously came in on a Saturday to give me a tour, they have identified the island in Japan from which the nematode came. It was not a species from Asia's mainland. 

Holden's main endeavor is to seek out beech that show some resistance to the disease, and test that resistance. 

Rachel first grows seedlings that can be used as root stock for these tests. The root stock serves as the bottom half of a graft.

When trees are found that have lingered in the landscape while others succumb, Rachel then grafts cuttings from these "suspiciously healthy" trees onto the prepared rootstock. 

Once the grafts heal,

the trees can be tested for resistance. Measured numbers of nematodes are applied to the buds, documented with colored tags, and the tree's resistance to the nematodes is then observed.

The nematodes are small enough to enter the buds between the overlapping bud scales. The tiny worm-like creatures inhabit the leaves all summer. Then in fall, exiting the leaves through the stomata--the openings on the undersides of the leaves through which the tree breathes--the nematodes transfer to the new buds to overwinter.

Each step in the process of testing resistance takes time and consistent attention. Rachel says some promising means of speeding research are in the works. Promisingly resistant trees can be propagated using only their leaves. The leaves are cut, a particular root hormone applied, then the leaf is stuck in soil medium to grow. This approach could potentially avoid the need to grow root stock, grafting, and the time it takes for grafts to heal.

As for treatments for the disease, she says soil applications of phosphite have mostly been experimented with on smaller trees because it's easier to study at these smaller scales. Similarly, using chemical sprays on the trees' foliage requires just the right timing, and a thorough coating, which makes larger trees very difficult and expensive to spray. They are experimenting with pruning to allow better air circulation and thereby reduce the moisture that the nematodes like.

ASH TREES

Research on resistant ash trees is a little farther along. Rachel showed me a grove of young green ash--protected by a deer fence--that are being tested for resistance to the Emerald Ash Borer (EAB), which spread through Ohio nine years before Beech Leaf Disease. This is the same introduced insect that has decimated Princeton's ash trees.

Rachel explained that the ash can defend themselves from the burrowing insects in three ways. One is a blockage that prevents entry. Another is to react by building a wall around an ash borer that has gotten in under the bark. Another is to somehow deprive the ash borer of nutrition, so that it becomes stunted. 

Sticky boards are used to monitor the presence of Emerald Ash Borers at the site.

When I told her that I had only seen one adult Emerald Ash Borer in my life, despite the hundreds of millions of ash trees killed, she pulled one off of the sticky board.

In this closeup, the Emerald Ash Borer is on the left; a native ash borer, far less destructive, is on the right. Though they are similar in appearance, it's the difference in behavior of the introduced species that has proven lethal.

She said that ash trees become vulnerable to EAB attack fairly early in life, certainly under ten feet high. While some of the ash trees being tested in the grove are dying due to EAB (perhaps these are the controls in the experiment), 

many are doing well, showing some degree of resistance. 

The green ash that have proven resistant to the EAB must not only be able to survive at low EAB levels, but also when the Emerald Ash Borer is present in high numbers. Rigorous testing helps avoid later marketing an ash variety that ultimately could prove vulnerable. 

This scar is evidence of an inner struggle by the ash to fend off the borer. The tree tries to build walls around the EAB larvae. 

Rachel described an autoimmune reaction, observed in black ash up north, in which the tree is too aggressive in blocking off passages, interfering with its own circulation. 

She talked about the physical aspects of doing research on trees and their pathogens. The wooly adelgid that plagues our hemlocks is hard to study, in part because it can be hard to apply the soft insect to test trees without squashing its soft frame, so they use its eggs. Nematodes are much easier to count and apply to branches.

Expanded greenhouses suggest Holden is expanding its efforts to nurture trees resistant to imported insects and disease. 

One bonus from my visit was that Rachel took an interest in our efforts in Princeton to bring back the native butternut (Juglans cinerea), and has put us in touch with someone studying the species.

If, as beech leaf disease takes its toll on beech trees in Princeton, we see some trees that "linger" and remain "suspiciously healthy," we'll want to notify Holden Arboretum, to aid their ongoing search for resistant trees. 

A thunderstorm prevented me from exploring the many gardens at Holden that day, including a treetop walk and tower. And then there's the Cleveland Botanical Garden closer into town, with which Holden recently merged. These are some good botanical destinations in Cleveland, with a mission that extends far beyond the city, and an engaging origin story.