Native Chestnut Update

While the discovery of Emerald Ash Borer in Princeton several weeks ago cast a big shadow on Princeton's most numerous tree, there's another shadow, growing larger every year, that's reason for hope. That would be the shadow behind this native chestnut tree growing at the Textile Research Institute (TRI) in Princeton. Planted just five years ago, it's now fifteen feet tall, well on its way to taking its place among the oaks towering behind it.

The protective collar around its trunk is beginning to unzip as the tree gets too big for its britches.

This marks the first year it has bloomed, though there may not be any nuts for lack of pollen from other trees. In future years, a less precocious companion planted nearby may catch up and provide that pollen.

These chestnuts, which are really 15/16th native, with some asian genes mixed in to aid in resisting the chestnut blight that laid this species low a century ago, were planted by Bill Sachs, a local nut tree expert who has planted chestnuts and butternuts in a number of locations in town. Butternut is another native tree much reduced in numbers due to an introduced disease.

Below is Bill's status report, from an email. It shows how much persistence and resourcefulness is needed to bring back a species, with a touch of serendipity now and then:

"Yes, I know the one chestnut at TRI flowered this year but there may be no nuts for lack of a pollinator. That tree was two year-old bare rooted stock when planted in 2010. Pretty precocious. Same generation as the ones we planted at Mountain Lakes (there are no healthy survivors left there) and on the Princeton Battlefield (two survivors, one of which has blight). This fall and spring, we may try to inoculate the trees that have blight with the virus that causes hypovirulence. 

There are three planted butternuts at TRI, all pretty close to one another. Two of them have been surrounded by blackberries and other brambles that need to be cleared. Will do that this fall… may need to rent a brush cutter.

Also, discovered a ‘new’ native butternut at ML with a few nuts on it. Been walking past it for years and this is the first time I noticed it because I happened to be looking up into the surrounding crowns to assess the health of the ash trees along the trail."

Bill

Harrison Street Park: Contrasting Tales of Trees and Wildflowers

Most people drive by Harrison Street Park unawares. It's an old neighborhood park that lacks parking, and so mostly serves those who live close enough to walk there. Whenever I think to stop by this surprisingly spacious park close to Nassau Street, it's to check in on dreams living and remembered. 

One dream is bringing back the American chestnut. We've planted a number of chestnuts around town that are 15/16th native. They were originally crossed with a resistant asian chestnut, then backcrossed with the aim of ending up with a predominantly native chestnut tree that still carries the Asian species' resistance to chestnut blight. Some of these trees have proven susceptible to the blight, but two in particular have resisted the blight thus far. One of these is in Harrison Street Park, nearly 20 feet tall now. 

We also planted two native butternuts there, another native tree that has been marginalized by an introduced disease. It's good to see them thriving and starting to bear nuts. 

There's also an attempt by the town, successful thus far, to keep a grove of ash trees protected from the introduced Emerald Ash Borer, via systemic applications of insecticide. Another small grove of trees was planted through a citizen donation and collaboration with the Shade Tree Commission.

Other dreams for Harrison Street Park, involving wildflower plantings, have not done so well. Princeton Borough had great dreams for this park at one time. In 2006, they hired me to conduct an ecological assessment and write a stewardship plan. Then they hired a landscape architecture firm from Philadelphia to design improvements to the park. Neighbors offered many ideas and expressed many opinions. The old wading pool--a relic from a distant, more sustainable era when kids gathered in their neighborhood parks in the summer--was removed, the play equipment was updated, and a few new features were installed. 

Some $30,000 was spent on new native plantings that looked good for a year or two before going into steady decline. The idea was that neighbors would care for all these new plants. Of course, a drought promptly ensued. Some of the neighbors rose to the occasion to keep the plants going, but the extensive flower beds required more than an initial season of zeal. Neither the borough maintenance crews nor any of the neighbors had the training or interest to keep the flower beds weeded over the longterm. 

This flower bed is now a massive stand of Canada thistle and mugwort. 

The plant with the big leaves is a common weed in the midwest that is showing up more and more in Princeton. It looks like rhubarb, but is in fact burdock. 

There's a swale in the park that receives runoff from a private parking lot next door. These wet, sunny spots can tip the balance towards native species. A friend and I planted various floodplain species--joe pye weed, tall meadowrue, etc--but also planted Jerusalem artichoke, which is a native sunflower species with edible tubers. 

When planting an aggressive plant like a native sunflower, it's easy to believe one will follow up and keep its expansionist growth in check. That's almost never the case. The sunflowers has spread aggressively underground over the years, and have long since swallowed the other wildflowers in their dense growth. Each year the sunflower clone expands, as park crews mow around its fringe. 

We also planted a couple pawpaw trees there, but they were overwhelmed by the sunflowers. A couple black walnut trees sprouted on their own and had much better luck, somehow managing to rise above the sunflowers. Trees that plant themselves tend to be more successful than trees planted by people. On the upside, the sunflowers are so aggressive that they require no weeding, and there's a dazzling display of yellow in the fall. But, like some of the other plantings at Harrison St Park over the years, it's not what was originally envisioned. 

Native American Chestnut in Princeton

It's been a long time since healthy leaves of an American chestnut were last seen in Princeton. True, there are a few remnant specimens of the species still sprouting from ancient roots, and these new ones are actually 1/16 asian, to confer resistance to the blight that devastated the American chestnut more than 100 years ago, but they're about as native as we're likely to get with the blight still around.

Nut tree expert Bill Sachs obtained the seedlings last year from an associate in Connecticut, planted them, and served as one man bucket brigade during the two month long drought last summer. His reward: the trees are flourishing this year, with one at Mountain Lakes having grown three feet this spring.

Wisteria's Tamed and Wild Twinings

The front porch of Morven has an educational feature for gardeners.

Go to the right side of the porch and witness Chinese wisteria twining up and to the right. 

Go to the left end of the porch and witness Japanese wisteria twining up and to the left. 

This contrast in twining direction appears to be a thing. There's agreement that the two species twine in opposite directions, but disagreement on how to describe it. The Japanese wisteria's winding up and to the left is described as either clockwise or counter-clockwise, depending on the website. The two websites I happened upon agree, however, that the direction of twining is not determined by whether the plant evolved in the northern or southern hemisphere. This is disappointing, as I had hoped for a pattern, which would be all the more satisfying if it happened to match the direction of swirl when water goes down a drain. Alas, some other force must be at work.

What Morven's porch won't show you is just how aggressive wisteria's twinings can become after a garden is abandoned. To comprehend the scale of expansion, you would need to travel to Herrontown Woods, where the extent of a wisteria clone (Japanese by the look of its twining) is still apparent in the woods. There are two clones, both covering more than an acre each. At their exuberant zenith, they had grown up and over trees and rendered the ground a monoculture of their foliage. One clone, up at Veblen House, is now mostly vanquished, in large part due to the extraordinary persistence in years past by Kurt and Sally Tazelaar. The success of that work depends, however, on ongoing vigilance to cut any sprouts still rising from the remnants of its sprawling root system. 

We are still very much in battle with the other clone, however, across the stream from the Barden. Each year for about four years now, the town has paid contractors to spend a couple days each summer applying systemic herbicide to this or that side of the monster. The herbicide is absorbed and translocated down, to weaken the wisteria's massive network of roots and runners. I think of it as comparable to the medicines we use to maintain our own health, well targeted and no more than necessary. 

Then, this past fall, a volunteer named Bill Jemas (posing in the photo with a wisteria vine) contacted the Friends of Herrontown Woods, looking for a good project to give him the equivalent of a workout in the gym. He came several times a week for much of the fall, working largely on his own, checking in with me periodically with a question or two. Cut, cut, snip, snip--he took on the still very intimidating tangle with hand tools and perseverance, making the hillside navigable once again, dotted with piles he made of the cuttings. He then announced his family was headed to Florida for the winter. Reportedly returning this spring, his contribution to the battle has already given us hope that the wisteria monster will not eat the Barden, towards which it was headed, and can be subdued like the one at Veblen House, so that we need only snuff out a few stray sprouts each year. 

A couple related posts:

Another Perilous Embrace--Wisteria and Horse Chestnut : About the horse chestnuts near Morven, and the horse chestnut that was getting overrun by wisteria in front of the 1755 house at 145 Ewing Street. Why does one often find a horse chestnut growing near a historic house? Because they bloom around Memorial Day?

Trees and Thunderbolts : The puzzling story on the Morven grounds of how a thunderbolt killed not the tree it hit, but the tree next to it.

Stony Brook Garden Club Chestnut Project

Here's another project in Princeton to bring back the American Chestnut. Thanks to Debra Costa for the information.

From Debra:
"I am heading our Stony Brook Garden Club project in our effort to help with restoring the American chestnut tree. All GCA clubs have an initiative to do some kind of civic tree project as a celebration of the 100th anniversary of the Garden Club of America - for 2013. We planted about 50 seeds on Sunday in Greenway Meadows Park.

The seeds were provided by Sara Fitzsimmons from Penn State University. She is involved in their research project of backcrossing toward the goal of a disease resistant tree. They are in their 6th generation of backcrossing. She heads and visits volunteer orchards connected with the project at Penn State.

At Sara's recommendation, we planted pure American seeds (not blight resistant) because of the need to maintain/provide a biodiverse germ pool of seeds for their back-crossing project. In time, with success of this "orchard" we can transition to blight resistant trees as they become more available."

Women and Wildlife Awards Event Today

The Conserve Wildlife Foundation is having its annual awards event today in Stockton, from 2-5pm. My group, the Sustainable Jazz Ensemble, will be performing as part of the event. Information about the three women receiving awards for their work to preserve New Jersey's threatened wildlife can be found at http://www.conservewildlifenj.org/getinvolved/women/.

One of the women, Jackie Kashmer, has been doing heroic work to save bats, which are being devastated by White Nose Syndrome. The fungus, which was recently determined to have been introduced some years back from Europe, disturbs the bats' hibernation, causing them to run out of stored energy before spring arrives.

Jackie's 16 hour days devoted to helping bats survive the winter, detailed in a conservewildlifenj.org blogpost, are an example of the extraordinary amount of work and devotion required to counteract to any extent the destructive impact of imported organisms.

By coincidence, the NY Times article reporting on the fungus's European origins was accompanied by an article on the reintroduction of the American chestnut in Appalachia. It has taken many decades for breeding programs to develop native chestnut trees resistant to the Asian fungus that began wiping out the American chestnut tree more than a century ago. These are the sorts of quiet, awe-inspiring efforts that seldom make it into the news, but make all the difference in what sort of world we'll have in the future.

Emerald Ash Borer in Princeton

Here's a stock photo of the recently arrived insect that will kill (there must be a better word) Princeton's most numerous tree species over the next decade. White ash, green ash, and the much less common black ash--all are vulnerable. The photo shows an ash tree with characteristic "D"-shaped exit holes. It will take a lot more than a penny to deal with the consequences of this diminutive beetle's appetite. I'll expand below, but I sent the quick read version out in a mass email that was then quoted in an informative article in the Town Topics:

"Emerald Ash Borer (EAB) was found in a trap set by the town arborist out along River Road. This small green insect, accidentally introduced to our continent from Asia, probably in wooden packing crates, has been spreading outward from its original introduction in the Detroit area, killing 100s of millions of ash trees. The insect will spread across Princeton over the next few years, eventually affecting all ash trees that haven't been treated. Highly valued ashes can be injected in springtime with an insecticide. The treatment can provide protection for several years. Of the various chemicals available, I've heard the most praise go to Arbor Mectin. Tree-Age has a similar formulation."

The Next Fifteen Years

So, what happens now, and what can we do about it? Princeton's arborist, Lorraine Konopka, sees this slowly evolving catastrophe following a fifteen year arc. In the first five years, EAB will spread around town, building up its numbers with each new generation. Symptoms are slow to manifest, but in various ash trees we'll start seeing dieback starting at the top of the crown and working its way down. Many ash trees are already suffering from ash decline, notably a disease called ash yellows, making it even harder to know for certain when EAB has invaded a particular tree. Homeowners will be forced to choose between spending hundreds of dollars every few years to treat favorite ash trees with systemic insecticide, or spending thousands of dollars later on to remove their dying ash trees before they become brittle and dangerous. The five years that follow will be marked by radical dieoff, both in town and in our nature preserves. Some woodlands where ash trees dominate will be decimated. We'll see otherwise green hillsides dotted with skeletonized remains of ashes. The five years after that, more or less, will see the last untreated ash trees succumb. The population of EAB will drop dramatically, but protected trees will continue needing new injections of insecticide, though potentially less frequently. Ash trees will still be found in nature preserves, but likely get attacked as they grow towards maturity. More on the aftermath at this post, written after a visit to Ann Arbor, MI.

Life Cycle

According to an EmeraldAshBorer.info webpage, the Emerald Ash Borer hatches into an adult in May and June (coincidentally, emergence is said to begin around the time that black locusts bloom), flies to new areas and mates in June and July, then lays its eggs in August. The larvae feed just inside the bark in the fall, then overwinter as pre-pupae before hatching into a new generation of adults the next spring.

So it's not surprising that the first confirmed sighting of an emerald ash borer in Princeton happened in late July, when one was found in a trap placed near River Road by the town arborist. Previous documentations in the area were in Bridgewater, West Windsor and other towns.

Treatment to Protect Ash Trees

Homeowners will need to decide, over the next year or two, which if any ash trees they wish to treat. The expense of recurrent treatments, and the ongoing benefits of the tree, need to be weighed against the cost of removal. This definitive article recommends treatment of trees if EAB has been found within 10-15 miles, which is now the case for Princeton. Treatment is most effective in the spring, between mid-May and mid-June, just after the tree leafs out. The article confirms the superior performance of emamectin benzoate, the active ingredient in Arbor Mectin and TreeAge. This insecticide may be more expensive than others like imidichloprid, but lasts longer and has a higher success rate. For more on my research on this issue, scroll down at this link to "How to save specimen ash trees".

Natural Predators of EAB

Woodpeckers are said to eat 80% of the EAB, but that's not enough to stop it. There are native parasitic wasps that also prey on EAB, but not in sufficient numbers. Some parasitic wasps species from the EAB's native range in Asia are being introduced (hopefully with a great deal of prior testing to show they won't prey on our native insect species), but I doubt they will influence the arc of Princeton's infestation over the next decade.

An article in the NY Times discusses techniques to stimulate the defense systems of ash trees so that the tree itself will manufacture sufficient chemical defenses to ward off EAB, but again, any practical use is highly speculative.

What's a Dead Ash Good For?

Strangely, there seems to have been no planning at any governmental level to at least put the coming surge in dead wood to use. Talk of sustainability and the opposition to fracking and natural gas pipelines are weakened if we ignore local sources of renewable energy. Lacking wind, we need to turn to sunlight. Solar panels, now essentially free to install, are an obvious option, but for some reason wood is being ignored. Europe has clean incinerators that generate energy from wood chips. Ann Arbor trucked its ash trees to an energy-generating facility in Flint. Unlike the carbon from fossil fuels, carbon from trees comes from the atmosphere, not from underground, so there is no net increase in above-ground carbon when wood is burned. Composting requires considerable fossil fuel for turning and transporting the compost, and decomposition releases as much carbon as burning.

In addition, the EAB invasion is coming just as Princeton's collection of loose yardwaste is being expanded. There is no effective incentive yet in place for homeowners to trim their dependence on this costly program, and the addition of 1000s of ash trees to this already over-burdened collection service could overwhelm the capacities of the public works department and local composting sites.

Possibly relevant, the state compiled this list of "Forest Industry Professionals Accepting Ash Trees".

Previous Posts

The Emerald Ash Borer's arrival in Princeton had been long anticipated. Some fifteen posts on this blog mention it, dating back to April, 2010, when I wrote,

"In Princeton, we will over the next decade likely witness a dieoff approaching the scale of the chestnut and elm dieoffs of the 20th century, as the emerald ash borer, which hitch-hiked to Michigan from Asia in wooden packing crates, continues its spread eastward. There will, in other words, be a lot of gaps in the canopy for the chestnut to claim, if its return is successful." 

That last part, about a resurgent American chestnut filling the gaps as we lose our ashes to the Emerald Ash Borer (EAB), as the previous post about chestnuts shows, was a nice concept but overly optimistic. Here's a particularly extensive post on EAB, in which I included notes from a phone call with the division chief of Forest Pest Management in Pennsylvania, where they've been dealing with EAB for years.

Botanical Tributes at Princeton Battlefield Threatened

If the plaque commemorating those who died in the Battle of Princeton got overgrown by vines, people would understandably be upset. But how about botanical tributes at the Battlefield? Mercer Oak The Second is doing well, carefully protected by fencing and no doubt periodically checked for health.

But there are other trees planted in memory of the battle that have been abandoned to whatever fate may come their way. Not far from the Ionic Colonade pillars are flowering dogwoods that were planted all along the perimeter of the north field. Those to the right of the pillars are doing fine. Those on the left are being smothered by vines--mostly porcelain berry and wild grape.

Some are so badly blanketed that you can't tell a dogwood is there until you peak under the mass of vines and see the venerable trunk of the dogwood holding up the free-loading foliage.

In this photo, porcelain berry leaves are on top, grabbing the sunlight from the flowering dogwood leaves below. I liberated a few of the dogwoods from the smothering vines some years back, but they really won't be saved until their protection becomes hard-wired into the Battlefield's maintenance. Here, again, the focus on lawn mowing to the exclusion of all other aspects of grounds maintenance has allowed an attractive and meaningful planting to be badly neglected.

It's really very simple for a crew to go in, cut the vines at the ground, maybe spray a dab of 20% glyphosate on the cut stem, and preserve these historically important plantings. It might add a couple hours a year of maintenance time.

The dogwoods also provide nutritious berries well timed with fall migrations, that is, if they get enough sunlight to power the production of the berries.

There are other plantings at the battlefield that are threatened, but not by lack of maintenance. We had high hopes for this 15/16th native American chestnut, planted in front of the Clark House. It's nearly 30 feet high now,

but I was recently told by Bill Sachs that the canker on its trunk--caused by the chestnut blight that nearly wiped out chestnuts a century ago--is not healing, suggesting that the tree will eventually succumb. Though this particular tree came out of a breeding program meant to generate blight-resistant native chestnuts, only about half of the trees will actually show resistance. Of the four chestnuts planted at the battlefield, two have succumbed, and this one may as well.

The fourth, however, is doing fine,

and Bill has already planted two replacements for the ones that died.

A larger question is whether the Battlefield wants to look anything like it did at the time of the battle. There were no lawnmowers back then, unless you count livestock, and these turfgrasses are not native to America. It's great to have a nice surface to walk on, have picnics, fly a kite, re-enact. Keep some turf, but should the landscaping really have nothing to do with historic accuracy?

Many battlefields around the country have made an effort to restore their landscapes to better reflect the era in which a battle took place. Mowing is very time-intensive, and most of the turf here is never walked on. The open feel is nice, but that could be maintained by reducing somewhat the mowed expanse, and restoring native grassland in unused areas, with broad trails through them kept mowed so that people can have the experience of walking through an authentic 18th century meadow. An orchard, too, would add some authenticity. But again, this means that an institution must go beyond lawnmowing in its conception of what constitutes caring for a landscape.

Begin, at least, with the dogwoods.

Birdwalk in the Mist

Plant people like me need extra motivation to show up for a birdwalk at 8am on a misty, moisty Sunday morning. Curiosity proved the deciding factor, specifically the question of whether clouds make birdwatching better or worse. The answer came quickly from seasoned birders. In words ascribed to Roger Tory Peterson,

"No sun, no bugs,
No bugs, no birds."

At the same time, we were seeing lots of birds, or rather, hearing them. The clouds wash out the colors, making everything up in the trees appear black and white. For quite awhile, walking along the gravel road leading into Rogers Refuge below the Institute Woods, there wasn't much lifting of binoculars. Rather, a rapt attention to calls emanating from the trees above. "Northern parula!", someone would say suddenly. "Yellow throat"! "There's a Maggie," which I took to mean Magnolia warbler. Not having a memory for what in music might be called the "upper partials" of the bird world--the songs of less common birds like warblers--I contented myself with recognizing the sputter of a red-bellied woodpecker.

Mixed with the staccato calls of the birders--"Pine warbler", "chestnut-sided"--were two overarching narratives running in contrary motion. One was of lost abundance. Bird numbers are down. What we see now pales in comparison to the 1960's and 70's. Those little green inchworms, so important to converting energy from the oak trees into energy for the warblers' northward migration, are now rarely seen, for reasons unclear. I suggested that the canopy is much higher now than it was forty years ago, so they may simply be out of sight, but hard to say.

The other narrative, more cheering, came from Winnie and Fred Spar, who lead the Friends of Rogers Refuge group. They speak of the resurgence in the shrub layer in the forest, which in turn has provided cover and nesting sites for ovenbirds and other species that have become much more abundant in the refuge. For the first time in 25 years, warbling vireo nests have been sighted there. And it's hard to be too glum when a chestnut-sided warbler is saying "Please, please, please to meet'cha". (check out bird mnemonics at this link).

The Friends group, of which I'm a part, can point to some initiatives that may be making a difference. Some water from the StonyBrook is getting pumped into the lower marsh this year to improve habitat. There's an ongoing battle to keep Phragmitis from taking over the upper marsh, and new birdhouses have been installed. But the biggest factor, less controversial than it used to be, is the hunting and professional sharp shooting that has brought the deer population more into ecological balance. Not many years back, the native spicebush that birds need in the understory had been decimated by the deer. Now it thrives.

People, in effect, through community policy, have taken responsibility for filling the ecological void left when the natural predators of deer were driven from the land. It's a story of how, even as widespread habitat loss and rapidly changing climate work against the birds, people can contribute to restoring balance and diversity.

Frogs are in even more rapid decline around the world, making this sighting of tadpoles particularly welcome.

I found the plants to be a lot easier to see than the birds. They stay in one place, and don't fly off when you approach. Very convenient, though it doesn't always make identification a snap. This small tree, discovered while I was doing an ecological assessment and stewardship plan for the refuge in 2008, still eludes attempts to give it a name.

Clearly related to cherries, it grows here and seemingly nowhere else in Princeton.

Just across the road was another unusual tree, a Golden Larch, whose scientific name, Pseudolarix, is latin for fake larch. Having two unusual species together suggests that the location was either a home site a long time ago, or was otherwise significant enough to be planted.

The golden larch's needles are longer than those typically found on a larch or our native tamarack.

You can see how even this tree's deep green turns black against the white sky. Despite this, we got good looks at the vivid colors of a scarlet tanager, a baltimore oriole and an American redstart.

We headed over to the bird blind, built by the Friends a few years ago, with windows reminiscent of an advent calendar. That's our Washington Crossing Audubon walk leader in front, Mark Witmer.

The walk continued around the refuge's marsh and into Institute Woods. We began talking amongst ourselves more and listening less. I was sidetracked by a patch of umbrella magnolia,

and then headed back to the car, my mind glad for the new population of bird names flitting from one neuron to another: "pine warbler, Canada warbler, hairy woodpecker, chimney swift....." The rain held off, the birds held forth, and curiosity is a good thing to hold on to.

Comeback Chestnuts and Butternuts in Princeton

On the 7th day of the 7th month, when the Brits via Andy Murray came back after 77 years to reclaim the Wimbledon men's tennis title, I took a hike with arborist Bob Wells to see some of the comeback kids he had found along the Princeton Ridge, in the form of native chestnuts and butternuts. Bob had recently conducted a tree inventory for Princeton, completing the township portion that can then be merged with the borough's. Along the way, he found a chestnut and a couple butternuts--species that have been laid low by introduced diseases. The number of naturally occurring specimens known to still be growing in Princeton can be counted on one hand.

I found Bob sitting in the woods near Bunn Drive with his dog, Mongo. While waiting for me, he had counted 21 woody species around him, a testament to the Ridge's diversity. Multiple kinds of hickories, maples and oaks, a beech tree, ironwood, cherry, tulip poplar, black birch, sweetgum, two kinds of Viburnum, witchhazel--learn to identify trees and you'll never be alone in the woods.

One of the other species was a solitary American chestnut tree of 6 inch diameter,

its distinctive leaves backlit by the afternoon sun.

One branch appeared already to have succumbed to the blight that laid waste this once dominant species of the eastern forests. The species as a whole went underground, its roots surviving, sending up suckers that would in time be killed off by the blight. Bob wasn't sanguine about this particular tree's chances, but at least it's still there, a century since the species was stricken by imported disease, still growing towards the sun.

Our next stop was further up the road, where clearing for the new Westerly Road Church had left a tall, gangly butternut out in the open. Though the native butternut (Juglans cinerea), also known as white walnut, was never a dominant species, and Princeton is on the southern edge of its range, its numbers have been reduced still further by an imported fungus.

Bob double checked the book's description. Thirteen leaflets, positioned opposite and stalkless, fit well,

and the dark brown pith. The trunk being hollow, Bob wasn't too optimistic about this tree's longterm chances, either, but to find a survivor is always reason for hope.

Heading around the bend onto Herrontown Road, Bob pointed out the thinned out foliage of a number of ash trees. Ash dieback, ash decline, something's going on with Princeton's ashes, and not much is known about the cause. Thinking it might be the arrival of the Emerald Ash Borer, the Asian insect accidentally introduced into Michigan that has been devastating ash trees on its way east, Bob arranged to have some traps set in the area. Results were negative.

To know and love trees is to realize that we cannot take our forests for granted, that behind the facade of static green is a shifting drama of competition, predicted demise, potential comeback, and mystery as engaging on its time scale as any sport. People play negative or sometimes positive roles in this high-stakes game. The easy accident of introducing a new disease to America is followed by a very long and hard struggle to save the species that are then pushed to the brink.

Our last stop was Autumn Hill Reservation, where Bob led me to a healthy butternut back in the woods, with room in the canopy to grow. I thought I saw another some 100 feet further off the trail, with impenetrable brush impeding our effort to confirm.

The bark of a butternut has a distinctive weave to the ridges. As you can see they've been known to sport a green trail marker, though they receive less compensation than famous athletes with product logos attached.

A few days later, I showed these trees to local nut tree expert, Bill Sachs, who has been growing and reintroducing American chestnuts and butternuts in various Princeton parks. He had located three butternuts growing naturally in Princeton, two of which have since been lost--one to a chainsaw, the other to flood and wind. Bob's discoveries bring the number back to three, plus all the seedlings Bill has grown.

We loppered our way through the invasive brush to reach what I had thought was an additional butternut 100 feet off the trail. A closer look proved it to be a black walnut.

Butternuts need more than one tree in order to bear nuts. The hope is that these few survivors have some level of resistance to the attacking fungi, and if we can start new groupings of these trees that will then bear seeds, these species can be coaxed back from the brink, to take their rightful place in Princeton's future.

Native Trees of Princeton

An attentive reader commented that the page for "Native Trees of Princeton", which I thought I had added along the top of the homepage, does not exist. Funny, I clicked on the "publish" button but the list of trees refused to publish, nor did it magically publish itself during the ensuing weeks when my mind was on other things. Maybe Googles ever more sophisticated software detected that it still needed work, which is to say it was a bit "drafty".

Here it is, nonetheless, published as a post rather than one of those enduring "pages" at the top of the blog. It was created as a step towards fleshing out, or foliating, a rather bare tree list we have on the Princeton Shade Tree Commission website.

My apologies to any native tree species not included here. Please speak up. Catalpas, we'll talk.

ATTRIBUTES OF SOME NATIVE TREES IN PRINCETON 

This is an extensive but informal list of native trees you may encounter in the wild or in your yard, with some description, based on ten years of observation. 

Acer negundo (box elder)--Grows wild. Not commonly planted. It's soft wood can provide good habitat for birds. Considered messy and not very well formed.

Acer rubrum (red maple)--A durable, very commonly planted street tree. Also common in the wild.

Acer saccharinum (silver maple)--Common in yards and in the wild. Not often intentionally planted. Has a reputation for dropping limbs, but performs well in many yards, providing an attractive, open shade.

Acer saccharum (sugar maple)--Less common, but a sturdy, attractive native.

Amelanchier canadensis (shadblow, shadbush, serviceberry, Juneberry)--A very small tree or large bush. White flowers early in spring, supposedly when the shad are surging up the Delaware. Berries edible, but frequently attacked by cedar apple rust, so don't get your hopes up. Even our resident catbirds were disappointed.

Asimina triloba (pawpaw)--Small tree, up to thirty feet. I heard there's a wild stand behind someone's house down across Carnegie Lake, and a substantial patch in a park over in Cranbury. Plant more than one to increase prospects for the often elusive fruit. They clone, so best planted where there's a little room to expand.

Betula lenta (cherry birch)--Grows wild along the Princeton ridge. Not commonly planted in yards.

Betula nigra (river birch)--Beautiful bark and form, frequently sold with three trunks.

Betula (paper and grey birches)--These species are more characteristic further north.

Carpinus caroliniana (blue beech, hornbeam, musclewood)--Common along the Princeton ridge. Not often intentionally planted.

Carya alba (mockernut hickory)

Carya cordiformis (bitternut, swamp hickory)

Carya ovata (shagbark hickory)--Hickories are common in the wild, but not frequently planted.

Castanea dentata (American chestnut)--Devastated by the imported chestnut blight in the early 20th century. Only a few small specimens persist in the wild. The disease does not kill the root, which then resprouts. Backcrossing has developed resistant native varieties with a small percentage of asian genes, e.g. 1/16th Chinese. Some of these 15/16th native trees have been planted in parks and preserves in Princeton in an effort to reestablish the species. A few chestnuts grow along streets in Princeton, but are either Chinese or Japanese. The nut husks are very large and prickly.

Celtis occidentalis (hackberry, sugarberry)--Sturdy native, infrequently seen in the wild, underutilized in planted landscapes. They line Walnut Street across from JW Middleschool.

Chionanthus virginicus (fringe tree)--Very attractive flowers. Small tree/large shrub. Some evidence in Ohio that it can be attacked by emerald ash borer, but more evidence is needed before deciding not to plant.

Cornus florida (flowering dogwood)--Attractive small tree, commonly planted, with berries that provide important nourishment for birds migrating south in the fall. Fairly common in the wild, but an imported fungus has cut back on its numbers. It can be harder to establish that the Korean dogwood, whose fruit are eaten by monkeys in its native Asia.

Crataegus crus-galli (cockspur hawthorn)--Attractive small tree. Rarely found in the wild. Underutilized in planted landscapes, perhaps because of thorns.

Diospyros virginiana (persimmon)--Attractive mid-sized tree. Females bear fruit, which may be appreciated or viewed as messy.

Fagus grandifolia var. caroliniana (beech)

Fagus grandifolia var. grandifolia (beech)--Beech trees are common in the wild along the Princeton ridge, but are seldom if ever planted.

Fraxinus americana (white ash)--Princeton's most common tree, soon to be decimated by the arrival of Emerald ash borer. Though typically encountered in second growth forest, it can grow to a towering height, with a few extraordinary specimens to be found on campus and in older neighborhoods. Planting ash is discouraged, since all ash species will soon be dependent on chemical injections for survival. Anyone owning an ash they wish to keep should get it treated, with emamectin being the most frequently recommended insecticide to inject into the trunk.

Fraxinus pennsylvanica (green ash)--Usually found in wetter conditions, and less attractively shaped, than the white ash. Same susceptibility to emerald ash borer.

Gleditsia triacanthos (honey locust)--The wild variety has thorns and is rarely encountered, perhaps because it was spread by now extinct megafauna. The unripe seed pods have a sweet, edible inner lining. One large specimen can be found near the old gas station at Princeton Shopping Center. Planted varieties, such as those at the new Dinky station and Hinds Plaza, have no thorns, and provide a pleasant, open shade. The tiny leaflets conveniently disappear back into the lawn in the fall.

Gymnocladus dioicus (Kentucky coffee tree)--A remarkable tree, rarely found in the wild, for reasons similar to honey locust. Its very large compound leaves emerge late in spring, and drop early in fall, making the tree ideal for planting on the south side of passive solar houses. They were used in the landscaping for the Dinky parking lot.

Hamamelis virginiana (witch hazel)--Attractive small tree/large shrub. The native species flowers in late autumn, while asian species flower in the spring.

Juglans cinerea (butternut)--Rarely seen. Some are hybrids. The native species has suffered from the introduction of a fungal disease. Efforts are underway to bring back the butternut in Princeton, in parks and nature preserves.

Juglans nigra (black walnut)--Common in some wild areas, and in some backyards. Rarely planted, due to large nuts and the juglone compound emitted by the roots, which can suppress growth of tomatoes and other plants.

Liquidambar styraciflua (sweet gum)--Sturdy, large tree, common in the wild and sometimes planted intentionally. The "gum balls" it drops can be a drawback for some.

Liriodendron tulipifera (tulip tree)--Fast growing, long-lived tree that can reach great size. Flowers tulip-like and attractive, but usually too high up to appreciate. Common in the wild, but not typically planted intentionally.

Magnolia virginiana (sweetbay, swampbay)--Small tree. Can have attractive flowers. Not typically planted along streets.

Morus rubra (red mulberry)--The white mulberry (M. alba, nonnative) is also found in Princeton. A small tree. Bears abundant, edible berries similar in appearance to blackberries. The berries can be messy, and the tree lacks an attractive form. Very tasty berries, though, if you can reach them.

Nyssa sylvatica (black gum, tupelo)--Beautiful fall color. Sporadically encountered in the wild. Long-lived, sturdy. Is becoming more frequently planted along streets.

Ostrya virginiana (ironwood, hophornbeam)--Small tree. Not common in the wild, nor in the landscape trade.

Oxydendrum arboreum (sourwood)--Small tree with bright red fall foliage. Craggy form. Underutilized; may not be well adapted for the nursery trade. More common in the wild further south. Several specimens in Princeton, including one next to the church across from the high school.

Platanus occidentalis (sycamore, plane-tree)--Can be confused with the London planetree, which is a hybrid between two species, one of which is P. occidentalis. Attractive, large tree, with highly ornamental bark. Its more susceptible to anthracnose than the hybrid.

Prunus pensylvanica (fire or pin cherry)

Prunus serotina (black cherry)--The native cherries are attractive mid-sized trees typically found in earlier successional forests. They nearly rival oaks in the diversity of insects they provide food for, and so are very important for food chains.

Quercus alba (white oak)--One of the most majestic trees. The white oak "family" (those with rounded lobes, such as white oak, swamp white oak, and willow oak) are less susceptible to bacterial leaf scorch than the red and pin oaks (pointed lobes).

Quercus bicolor (swamp white oak)--Sometimes planted along streets.

Quercus coccinea (scarlet oak)--Attractive, but less commonly planted.

Quercus palustris (pin oak)--Very common street tree in Princeton. Its lower branches characteristically angle downward and often die back. Many are being lost to bacterial leaf scorch, which causes gradual dieback.

Quercus phellos (willow oak)--More frequently planted than in the past. More common in states further south. Its narrow leaves can form an attractive mulch, somewhat like pine needles.

Quercus rubra (red oak)--Common tree in the wild and along streets. Susceptible to bacterial leaf scorch.

Quercus velutina (black oak)--Encountered in the wild. Less commonly planted than red oak.

Robinia pseudoacacia (black locust)--Native to the Appalachians. Widely planted and naturalized elsewhere. Its wood is resistant to decay, it has attractive flowers, and can achieve a very attractive form with dark, craggy limbs contrasting with the foliage. Can be invasive in some habitats, and can clone, sending up young shoots armed with thorns. But some specimens in Princeton front yards are beautifully formed and well behaved.

Salix nigra (black willow)--Fast growing. Sometimes planted in low areas in the belief that it will dry the soil out.

Sassafras albidum (sassafras)--Attractive tree, common in the wild. Can clone, which may be why it's not commonly planted.

Tilia americana (American linden, basswood)--Attractive. Underutilized. Sporadically encountered in the wild. Linden trees along streets are generally not the native species.

Ulmus americana (American elm)--Though the elm was hit hard across America by Dutch elm disease, Princeton varieties have shown considerable resistance, allowing specimens to perform well and provide shade for many years, even though they may eventually succumb.

Ulmus rubra (red elm, slippery elm)


Native Evergreen Trees:

Ilex opaca (American holly, Christmas holly)--Attractive native, sometimes used in yards. Can grow eventually to 30 feet or so.

Juniperus virginiana (eastern red cedar)--Small tree. Useful in some situations.

Pinus strobus (eastern white pine)--Not encountered in the wild unless in planted stands. Its native range is to the north of Princeton. Can get big, and tends to drop large branches during ice storms.

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.