Doing Battle With Invasives at Princeton Battlefield

The Princeton Battlefield that people see while driving by on Mercer Street looks peaceful and under control, a broad expanse of closely mowed turf interrupted only by a few scattered trees. Nature is subdued, as on a sports field, the better to have a picnic, fly a kite, or show off the periodic reenactments of human conflict. This Saturday, April 11, for instance, a British regiment will show up as part of the ongoing programming organized by the Princeton Battlefield Society.

There are, however, real battles going on right now, hidden along the edges of the field. Some pit one plant against another, day after day, breaking only for winter, like the porcelainberry and other vines mobbing the dogwood trees planted back in the 70s to ornament the northern field. And behind the Clark House, a patch of bamboo is expanding its claim to the land. Its encroachment on the trail to the Friends Meeting House has caused the Battlefield Society volunteers to take up loppers and saws against it.

That annual skirmish was waged during March 28's cleanup day, with assistance from Sierra Club volunteers.

Some were cutting and sawing, others were hauling the 20 foot stalks over to a pile,

where some stalks were lined up, somewhat reminiscent of what must have been done with the casualties in a real battle.

This comparison of invasive plant control to a battle may be unsettling for some who prefer to associate nature with peacefulness. There are, to be sure, lots of examples of win-wins in nature--the mutualism of pollinators and flowers being the most common example. But even the peaceful appearance of the expansive lawn out front is achieved only through the covert violence of whirling blades in the mowing equipment.

We could say live and let live, and give the bamboo and porcelainberry free reign, thereby providing ourselves with a convenient excuse to do nothing while claiming a superior tolerance towards all other living things. But all gardeners play a game of winners and losers, pulling out one plant so another might thrive. And the plants themselves are not particularly peaceful towards each other. The bamboo with its stifling shade, aggressive roots, and expansionist agenda is the epitome of intolerance, of "not playing well with others".

Right next to the bamboo is another example of how laissez faire policies can lead to domination by one highly aggressive plant species. Porcelainberry has turned a small stand of trees into a giant topiary. The vines in the foreground were severed near the ground--an easy way to at least temporarily liberate the tree and cheat the vine of all the solar energy it might otherwise have collected while using the tree trunk as a prop.

If they're not cut, the vines overtop the tree and grab all the sun. The tree weakens, a strong wind or ice storm comes along, the weakened tree falls. The result looks like the tree was actually tackled by the vine, which in some ways it was.

When I was a kid, we staged battles occasionally. I remember having a tiny cap gun. Sometimes it was cowboys and Indians, sometimes a spontaneous reenactment of the Civil War on the wooded slope near a friend's house. I grew into a peace-loving adult, and yet some aspects of that strategic thinking utilized in war have parallels in open space management. Since an army's fearsome tanks are useless without gasoline to power them, then one way to win the war is to deprive them of fuel by bombing the aggressor's refineries. If they start rebuilding the refinery, don't bomb again immediately but instead wait until they are almost done rebuilding, then destroy it again just before it can produce any gasoline.

That is exactly what the Allies did in WWII, and a very similar approach can be used against bamboo. Cut it all down--completely, every last stem--so the clone is entirely cut off from its solar energy source. Then wait for it to send up new stems. Those stems will rise 5 or 10 feet before sending out any leaves that can start collecting solar energy. Just as the bamboo shoots start sending out leaves, cut it all down again. The roots have spent all that energy sending up new stems, yet will have nothing to show for it. Since the roots are also continuously spending energy just to stay alive, then the fewer leaves there are to feed that demand, the sooner the roots' reserves will be depleted. Stick with this war of attrition, and the giant will be slain.

And what will the Battlefield Society do on volunteer days if several strategic interventions in a single season weaken the bamboo so that it is no longer growing into the trail, or into the remains of the old barn? I'm sure there's a long list somewhere.

One of the perks of doing invasive species work is that it takes one where one might not otherwise go. I've visited the battlefield many times, but only the fight against bamboo led me to where there are ruins of an old barn.

There was a brief timeout to contemplate the possible origin of holes in one of the foundation stones.

Invasive species removal is one of the few ways we can experience outdoor work, and in some small way reenact the physical exertion once necessary to make this farm a vital enterprise.


Some notes: Bamboo is a grass, like corn or sugar cane or sorghum, or the Arundo donax from which reeds for instruments are made, or the massive stands of Phragmitis that invade many wetlands. Before Rachel Carson wrote about DDT, she wrote about Spartina, the remarkable grass that dominates salt marshes. There's a bamboo native to North America--Arundinarea gigantea--which once formed expansive canebrakes in the southeast. Escaped slaves would hide in them. The native species mostly survives today in names like "Reed Creek" while the exotic bamboos dot the urban landscape. When I lived in North Carolina, I saw the native species only a few times in scraggly remnants. 

If you think about it, you've probably never seen bamboo flower. A grove of bamboo will live for many decades without flowering, then flower and produce seed en masse, just before dying. The vast amount of seed suddenly produced by the native cane must have overwhelmed the capacity of wildlife to consume it, though some sources suggest that two lost bird species--the carolina parakeet and the passenger pigeon--were able to make the most of these rare bursts of abundance. I saw a flowering and sudden dieback of exotic bamboo in Durham, NC once, when a patch covering a whole city block flowered and died. There are a lot of homeowners in Princeton who wish their bamboo would do the same.

Bamboo at Princeton Battlefield Gets its Summer Cut

This past Saturday, four of us gathered for a well-timed intervention at the Princeton Battlefield. The Friends of Princeton Battlefield had cut down a patch of bamboo in the spring, but the roots had quickly sent up a new crop of shoots--essentially foliar solar panels that would quickly begin resupplying the bamboo's powerful root system. By following up and cutting the new shoots, we deprived the roots of any return on their investment in new infrastructure. This is the third year we've done this, and each year the job gets easier. A massive stand of bamboo has been reduced to modest sprouts easily managed.

Thanks to volunteers Jill Warrington, Andrew Thornton, and the leader of the Friends of Princeton Battlefield, Kip Cherry. My participation was a bit of outreach from the Friends of Herrontown Woods, on the other side of town.

15 Flowering Dogwoods Rescued from Smothering Vines at Princeton Battlefield

Saving legacies is what Princeton Battlefield is all about, and one legacy we sought to save during a big workday organized by Kip Cherry were flowering dogwoods planted for the nation's bicentennial in 1976. I do most of my habitat restoration work at Herrontown Woods in eastern Princeton, but have been visiting Princeton Battlefield periodically to help tame bamboo monsters, care for native chestnuts and prevent vines from completely smothering the dogwoods. Having ten able and spirited volunteers at this year's Battlefield Society's Clean-up Day made real progress possible.

Kip Cherry (front left) began the afternoon with a moving description of the great battle that took place there in 1777.

Ten of us then headed across Mercer Street to liberate the flowering dogwood trees lining the edge of the field. The dogwood flower buds, poking through the drapery of vine growth, provided inspiration, with their promise of beauty in the spring, and nutritious berries for the birds in fall.

This was the curtain of vines we cleared away with loppers and pruning shears, while dodging poison ivy and the thorns of multiflora rose.

Here's a "before" shot, showing porcelainberry draped over three dogwood trees. (photo from last fall in a previous post)

And here's the "after" shot, taken from underneath the rescued dogwoods. We worked to create an open space between ground and lower limbs so the vines cannot easily climb back up.

Thanks to our brave and skillful crew, who came from near and far to liberate fifteen dogwoods over the course of three hours.

I liked this pose when the work was done. As always happens on workdays, there were good conversations to go along with the physical work. I gained some Veblen House-relevant information about Long Island and Connecticut, and heard some positive testimonials about electric cars like the Chevy Volt, which combines 60 mile battery range with a backup gas engine. One owner said she'd spent only $9 on gas since last summer, and hadn't noticed any rise in her electricity bill from charging up the car at home. While restoring some history, it was good to hear the future in the form of electric cars might be at hand as well. The same thinking goes into saving legacies, whether they be dogwood trees or the world's climate.

Senator Kip Bateman and Assemblyman Reed Gusciora dropped by to help out.

Here is Kip Cherry's summary of the day:

"Our Clean-up Day was a big success! The sun peaked out, and from all reports everyone had a great time, the Park looked a lot nicer when we were done, the CWT t-shirts were well received, and the Sierra Club came through. Senator Bateman and Assemblyman Gusciora both arrived and put their shoulders to the wheel. A large group of kindergartners picked up fallen sticks, while others removed invasive porcelainberry vines from dogwoods, cut down bamboo, and cleared encroachment along the pathway to the Quaker Meeting House. Special thanks to Kim Gallagher and Steve Hiltner for leading teams, and to Gary Nelson and Randy Riccardo for their hard work!"

Some Horticultural History: Dogwoods at Princeton Battlefield

Here's a little story that shows how the past can enrich the present and inform the future. Two years ago, I was over at the Princeton Battlefield, in that immense mowed field on the north side of Mercer Road (the side with the columns), and noticed a pattern in the wooded edges of the field.

It's most obvious during April, when these flowering dogwoods advertise their position, but you can see it as well in the autumn when their leaves turn radiant colors.

The dogwoods are spaced all around the edge of the field, but on the left side they've been completely overgrown by vines. It's a matter of time before the shade and weight of the vines weaken and ultimately kill the trees.

Hopefully, a workday to cut the vines can be arranged soon with the Friends of Princeton Battlefield. Recent Veblen-related research of old newspapers has solved the riddle of who planted the trees and when, and may provide further impetus for action to save the beautiful trees. Turns out the trees were donated back in 1976 by the Dogwood Garden Club, which still exists. Among its current projects is care of one of the gardens near the Princeton swimming pool entry. The relevant text from the article is in bold.

Town Topics, 2 December 1976

The annual Christmas Auction and Bake Sale of the Dogwood Garden Club will be 5 held Thursday, December 9. 1 in the home of Mrs Michael ; Jensen, 18 Riverside Drive ' West Co-hostesses will be Mrs William Alston, Mrs. Joseph Pierson, Mrs. Richard Olsson and Mrs. Frederick Wightman Jr. Mrs. Dudley Clark will serve as auctioneer. All articles to be auctioned have been made by the members and all proceeds will be used in cooperation with the Mercer County Park Commission to continue the restoration and maintenance of the memorial garden around the home of Mrs. Oswald Veblen in Herrontown Woods. In honor of the Bicentennial the club recently gave 25 dogwood trees to the Princeton Battlefield Preservation Society to be planted on the grounds. 

Mile-a-Minute Vine in Princeton

Each year I conduct a solo campaign to keep the highly invasive weed Mile-a-Minute out of Princeton. It's a prickly annual vine that grows each year from berries produced the year before. Knock it out before it produces berries, and eventually there will be no berries to sprout. Otherwise, the infestation will grow and birds will spread the berries across all of Princeton, to spring up in backyards and vex homeowners with its thorns and rampant growth.

I know of two infestations--one at the Princeton Battlefield, the other down off West Drive on the gravel road to Rogers Refuge. Yesterday, passing by Princeton Battlefield, I stopped to uproot what Mile-a-Minute I could find and leave it on the lawn to dry in the sun. Like most annual plants, it has whimpy roots and can easily be pulled, wearing a good pair of gloves.

Princeton Battlefield has a remarkable history, which makes it all the more remarkable how ahistoric the landscaping is. Non-native turf is surrounded by giant kudzu-like topiaries of non-native porcelainberry vine growing over the native dogwoods that were proudly planted for the 1976 bicentennial. There's little hint of what the Clark Farm looked like on that fateful day in January of 1777. The lack of botanical context doesn't fit with the people and era the Battlefield is meant to celebrate. Plants were important to George Washington and other leaders of his time. They were farmers. It's not coincidence that the United States Botanic Garden was built to stand next to the U.S. Capitol building. What grew upon the land mattered back then. They didn't mow the lawn and think their work done.

Seeing a landscape so invaded and out of balance, I sometimes imagine a hospital with no doctors or nurses, only custodians dedicated to keeping the place clean. The patients are on their own, unless a volunteer doctor happens by to treat some localized infection. That's the situation in the vast majority of our landscapes, cared for by custodians armed with raucous mowers and leaf blowers, oblivious to the complexities of nature and its needs. 

In the meantime, I pull the Mile-a-Minute, trim back some small portion of the porcelainberry vines so the dogwoods might live another year, and wonder at the world's disconnect with nature.

The two photos show 1) porcelainberry vines overwhelming a dogwood tree, and 2) another sea of porcelainberry in which only the similarly invasive Canada thistle can manage to lift its pink flowers above the swarm.

Bamboo at the Battlefield--Year 2

Whatever purpose this bamboo patch at Princeton Battlefield was originally supposed to serve--screening?, poles?, bamboo shoots?--its expansionist tendencies have led to ongoing attempts to eliminate it. Last year marked a turning point in the battle to prevent the giant clone from blocking the old trail between Clark House and the Stony Brook Meeting House. Because of strategic interventions in both spring and early summer by the Battlefield friends, all that remained this spring of the mighty stand were low, grassy clumps of bamboo leaves huddled near the ground. However, as expected, the root system still had enough energy to launch a new generation of strong vertical shoots this year, aspiring to regain its lost ground and resume its expansion into the trail and the area where a barn once stood.

Protecting these historic features of the Battlefield means returning again this June to cut down the new stems before they can start collecting solar energy. Since expansionist plants can be so daunting to counter, it's satisfying to intervene when the stems are soft and easily cut with a pair of loppers.

Just across the path, the volunteers left a big pile of porcelainberry vines cleared from a patch of ground they wish to reclaim from the "kudzu of the north".

There's a native plant mixed in. Beneath the grape-like leaves of the porcelainberry is a sea of the lighter green leaves of jewelweed, whose tubular orange flowers attract hummingbirds.

Princeton Battlefield Clean-up -- March 31

Each year, the Princeton Battlefield Society and the local chapter of the Sierra Club team up to have a volunteer workday at the Battlefield. Though the Battlefield is a state park, the state limits its maintenance of the grounds to lawn mowing, leaving the rest of the park's greenery to grow as it may. Two very aggressive introduced species, bamboo and porcelainberry, have run rampant, impinging on trails and overwhelming some historic plantings such as the dogwoods planted in 1976 to celebrate the nation's bicentennial. As part of the Friends of Herrontown Woods' outreach, I'll be leading volunteers interested in sustaining the dogwoods planted around the perimeter of the park on the Colonnade side.

Anyone who'd like to join in, check out the flier below, and rsvp at https://www.theprincetonbattlefieldsociety.org/. If you can, bring workgloves, loppers, and handsaws. Here's a writeup on last year's spirited event, with our state senator Kip Bateman in attendance.

Porcelainberry: the Vine that Ate Princeton

Here it's Friday of National Invasive Species Awareness Week, and nary a post about invasive species!

First, readers should be aware that there are contrarians out there, writing books, articles and opeds, trying to deny that invasive species are a big problem. It's fascinating to analyze their mental gymnastics and deceptions, which are similar to those used to deny the reality and danger of climate change. I've picked apart their faulty logic in posts that can be found at this link.

Now, on to our porcelainberry tour of Princeton. You won't find it in shady areas, where other invasives like stiltgrass, garlic mustard and winged euonymus thrive. Rather, porcelainberry threatens to smother all of those sunny openings and edges that shade-intolerant plants depend on for survival. Porcelainberry is related to our wild grape, but much more aggressive. Your first impression will be, "What lovely multicolored berries!"

Your second impression, as it climbs up the stems of your shrubs, like this elderberry, might be, "Oh, a little rambunctious, but those berries are so pretty!"

Your third impression, as it turns your yard or park into a monocultural topiary, will be more along the lines of, "OMG! HELP!" No, this is not kudzu growing along a freeway down south. This is porcelainberry winning a modern day Battle of Princeton, with stealth and persistence far beyond anything we distracted humans might muster.

This is what a nearby patch looks like in December, just down the road from the Princeton Battlefield, along Quaker Rd between Mercer and 206. Invasive vines and shrubs can seem less overwhelming in winter, which is actually a good time to remove them. In spring and summer, though, all that growth energy can be intimidating.

And this is what porcelainberry is doing to the sunnier portions of our lovely nature trail off the DR Canal Towpath near Harrison Street. The blackbirds may say hello to the berries, but it's bye bye to the diversity of native wildflowers underneath that foliar blanket.

Turns out porcelainberry's a soccer fan. Here it is in the cheap seats at Princeton University's Roberts Stadium, at one end of the field,

and at the other.

Here it is (light blue and pink berries) in that "second impression" stage, climbing over a honeysuckle shrub (red berries) at Quarry Park. Give it a few years and it may reach the "OMG" stage.

I haven't seen much of it in eastern Princeton yet, but we'd be smart to keep an eye out and remove it before the berries mature.

Otherwise, sunny edges everywhere will look like these hapless flowering dogwoods, planted at Princeton Battlefield in 1976 for the nation's bicentenial, and now struggling to survive beneath a spreading blanket of porcelainberry.

Note: You can help liberate the dogwoods from the porcelainberry and other vines on Saturday, April 1 at 1pm. I've been collaborating with the Princeton Battlefield Society on invasive species work for the past several years, and will be leading a group to preserve the dogwoods that line the field on the north side of Mercer Street.

Another group of volunteers will be continuing the multi-year effort to reduce the bamboo clones near the Clark House, which we're actually having considerable success without herbicide. 

For purposes of identification, here are a couple closeups of porcelainberry. The berries are distinctive, with different shades of blue, red and white.

The leaves are easily confused with wild grape. This photo shows how variable is the shape.

I hope everyone's having a happy National Invasive Species Awareness Week. We'll end with a short Q and A:

• Are all nonnative plants invasive? No. Nonnative refers to origin. Invasive refers to behavior.
• Why are invasive plants invasive? Oftentimes, it's because the native insects/deer, etc don't eat them, giving them a competitive advantage. To regain the balance we lost by introducing species that evolved elsewhere, people end up having to be the herbivores, wielding saws and loppers.
• One nice thing about invasives? They get us out in the woods for workdays. 

Princeton Battlefield--Big History, Big Lawn, Big Trees

One of the finer ways to spend a July 4 afternoon is on the grounds of the Princeton Battlefield. Chances are, you'll see historian John Mills, who in stature, bearing and voice seems the very embodiment of 1776, offer a detailed account of the Battle of Princeton, and then don spectacles to read the Declaration of Independence.

It's also a good place for a native plant lover to feel ambivalent about the extraordinary expanse of mowed grass. It makes for a great feeling of openness and freedom of movement. On the other hand, it has nothing to do with the history of the place, and is surely a budget drain to mow.

Other historic sites around the country have started to manage for more authentic vegetation. One approach would be to keep a portion of the grounds mowed, while planting the rest to the sorts of native grasses and wildflowers that have more to do with the land's history. Some of the grounds are already managed this way.

Most everyone knows about the Mercer Oak, whose offspring now grows in the middle of the field near where the original white oak once stood.

There are some other interesting trees there as well. I'd heard that the grounds include two Hicans--a cross between a hickory and a pecan. The bark on the tree in the photo looks like a hickory for the first eight feet, then switches to pecan-like bark further up. Strange.

Closer to Clark House are a couple chestnut trees. These are Chinese chestnuts, not the great American Chestnut that once filled our forests and provided abundant food until the imported chestnut blight took its toll. The Battlefield would be a great place to reintroduce the American Chestnut, survivors of which have been bred to resist the blight.

Some other interesting trees, just behind the Clark House, are some very tall, statuesque black locust trees.

Invasive Plant Species in Princeton

This Monday, May 22 at 7pm, the Princeton Public Library will host a presentation on invasive species in Princeton by Mike van Clef, of the NJ Invasive Species Strike Team. There will also be representatives of FOPOS and DR Greenway participating. Princeton municipality hired Mike to develop a report on invasive species in Princeton preserves, and in 2016 he and two interns worked through the summer on invasive species control. Because of the massiveness of the problem, they focused on emerging species--those whose populations are still small enough that a summer's worth of control would make a difference. 

We may look back on 2016 as a pivotal year, when the town began investing in invasive species management, much as 2000 marked the beginning of professional deer management in town. 

Although it may sound self-congratulatory, another important date in Princeton's history of invasive species management would be 2006, when the Friends of Princeton Open Space hired me as their first Natural Resources Manager. 

When I arrived in town in 2003 on the coattails of my wife's appointment to the Princeton University faculty, a couple things quickly became obvious. First, Princeton had done wonderful work preserving land for open space. Second, the open space itself needed a lot of work. Though the trees in Princeton's woodlands were mostly native, the understory vegetation was often dominated by nonnative, invasive plants. Stiltgrass, honeysuckle and privet, to name but a few, had filled the void created long ago when the diverse native understory had been plowed under, back in Princeton's agricultural era. In the decades since, the native trees had rebounded, but the understory had either not come back, or succumbed to heavy browsing pressure from deer.

Because wildlife tend not to eat the leaves of nonnative plants, their proliferation in preserves renders the habitat largely inedible. Yes, birds can eat the berries of nonnative shrubs like honeysuckle, but if the insects and other wildlife aren't eating the leaves, then much less of the solar energy captured in the plants can move up the food chain. 

I proceeded to make the case that Princeton could expand its effective acreage of open space through management for native species. As most readers know, I've been leading workdays and nature walks ever since, for six years as an employee of FOPOS, and more recently as president of the Friends of Herrontown Woods (FOHW). Highly motivated volunteers like Tim Patrick-Miller and Andrew Thornton, and more recently Kurt and Sally Tazelaar at Herrontown Woods, have had a positive impact over time. Meanwhile, FOPOS has sustained its Natural Resources Manager position--having just hired the fourth to hold that position--and continues to do invasive species removal at Mountain Lakes Preserve. After so many years of nonprofit, largely volunteer efforts, to finally get municipal support through Mike's crew this past summer was a real boost that we hope will continue.  

It's important to note that Mike van Clef's study of invasive species in Princeton is limited to parks and preserves owned or managed by the town. There are large expanses of open space owned by the state (Princeton Battlefield and DR Canal) and by the Institute for Advanced Study (the 600 acre Institute Woods). Portions of the Battlefield and the DR Canal are being overrun by porcelainberry (in photo), which barely registers in Mike's survey, and mile-a-minute vine is beginning to show up there as well. I've been trying to help fill a void in management, co-leading workdays at the Battlefield and, in the proactive "early detection, rapid response" tradition, dealing with two small infestations of Mile-a-Minute in town before they become unmanageable. Another nonnative plant that's spreading rapidly, both in people's yards and in nature preserves, is lesser celandine (a.k.a. fig buttercup). It can only be controlled in the spring, long before summer interns begin work. Ideally, a town-wide coordination to manage invasive species would be developed.

The town's investment in invasive species control comes at a critical time. With the emerald ash borer (another highly invasive introduced species) poised to decimate Princeton's most numerous native tree, large gaps will be created in our forest canopy, allowing light to penetrate to the understory. Princeton's long investment in deer culling has allowed native shrubs like spicebush to make a comeback, but in many woodlands, the understory is dominated by nonnative shrubs and stiltgrass. Wildlife have evolved over millenia to eat native species. It's a question of whether edible natives will capture that extra sunlight in the understory, or the privet, winged euonymus, honeysuckle, barberry and Photinia. The foodchain depends on our intervention.

The primary argument for habitat management remains that, by improving the quality of habitat, Princeton effectively increases the functional acreage of open space. This is true not only for wildlife but also for people. Controlling invasive species also makes the human experience in preserves more rewarding. As we've cut down invasive shrubs at Herrontown Woods, we've not only made more sunlight, water and nutrients available for native species to prosper, but also have opened up pleasing vistas and made the woods more navigable. 

The problem of invasive plants may seem overwhelming, but we can take our inspiration from the deer, who transform landscapes through the cumulative impact of browsing here, there, and everywhere, one mouthful at a time. The pioneers, too, thought the continent too vast to ever tame. Though their goal wasn't exactly to increase native plant diversity, they showed how steady effort makes a difference over time. Ideally, professionals will complement existing volunteer efforts, and the locals who know the preserves best will help steer the professionals' interventions. 


At Monday's presentation, there will also be discussion of a list of invasive species that people are being discouraged from planting. It's a very long list, and I wish it could better reflect the broad spectrum of invasive behavior we see in the field. One reason the list is so long is that, though many of the species on the list may not be found spreading into Princeton's nature preserves, history shows that invasive behavior in nonnative species may not become manifest until many decades after they've been introduced. Chinese silver grass (Miscanthus sinensis) is a case in point. Though it has yet to spread to Princeton's Tusculum meadows, it is now posing a big problem for meadows at Duke Farms up in Hillsborough. The flyer for the library event includes a photo of butterfly bush, which I've never observed exhibiting invasive behavior. Monday's presentation may help put local observations in a broader context.

Update: Full house for the program! Good to see.

Native Bluestem at the Princeton Battlefield

In an expanse of exotic turf grass at the battlefield, a few clumps of native bluestems pop up between mowings to show what used to be there in centuries past. Little bluestem, big bluestem, broomsedge, Indian grass, purple top and switchgrass are all tallgrass prairie species that can be found growing in Princeton in meadows and along right of ways where annual mowing keeps tree species from moving in.

I periodically contact the battlefield caretakers with the idea of restoring the landscape there to a more historically authentic condition. They have it in their longrange plan. The mowed grass is great for flying kites and throwing frisbees, but there's far more mowed expanse than I've ever seen actually being used.

One section--in the distance in the first photo--is mowed annually, allowing the bluestems and other prairie species to grow to maturity.

Saving Bicentennial Dogwoods at Princeton Battlefield

The big Princeton Battlefield/Sierra Club workday earlier this month didn't include attending to dogwoods along the field's edge, but the care we gave them in previous years to liberate them from porcelainberry and other aggressive vines is still serving them well. Some historical research revealed that they were planted by the Dogwood Garden Club for the country's bicentennial celebration 42 years ago.

Back in 1976, before the deer population exploded and aggressive invasive vines spread across the landscape, it was probably much easier to sustain plantings like this. The planting design was logical enough, with daffodils on the ground in front of the dogwoods, and white pine trees forming a nice evergreen backdrop behind.

But now, the daffodils are obscured by invasive shrubs and brambles, and the dogwoods find themselves growing in a sea of porcelainberry vine on the ground that, if not controlled, will quickly rise into the dogwoods to smother them. Meanwhile, the pine trees that now loom large behind the dogwoods drop big branches during ice storms. It's a one-two-three punch that takes concerted effort to counteract, and the state agency in charge of maintenance tends only to the lawn, with little or no on-the-ground knowledge of plantings that have any complexity beyond trees and turf. Volunteers can sometimes fill the gap. Last year's workday was particularly spirited. We cut vines and competing woody growth away from fifteen dogwoods, so that they could continue to ornament the Battlefield and feed migratory birds in the fall.

But like Mr. Incredible says when interviewed at the beginning of The Incredibles movie, the world refuses to stay saved. Already, the porcelainberry is sending new shoots up into the dogwoods, and until some animal or disease comes along to limit the vine's rampant growth, people will need to intervene to sustain some sort of balance that allows the dogwoods to grow.

Meanwhile, out in the fields, delays in mowing have made it possible for the cuckoo flower (Cardamine pratensis) to bloom.