The Very Dramatic Caterpillar Eating Wild Blueberry Bushes

Before I saw the blueberries, I saw the caterpillars eating the blueberry bushes. They were distinctive in the braiding of their bodies into a cluster on the stem. I snapped a photo of their distinctive black heads, yellow necks, and striped bodies, and must have brushed against the bush, because when I looked at them again, surprise!

They had all contracted their bodies into a dramatic pose that completely hid their heads, as if they were the caterpillar world's equivalent of a synchronized swim team. What's the logic here? Look down and away and the potential threat will disappear? Seems human, somehow--a caterpillar's artistic pose to symbolize society's head-in-the-sand response to climate change.

A nearby bush had been stripped of leaves but still had a few blueberries.

While highbush blueberry bushes tend to be solitary, the lowbush blueberries I have seen in woodlands, whether in North Carolina, on top of New Jersey's Mount Tammany, or in Princeton's Herrontown Woods grow clustered in colonies on a hillside.

These heavily shaded patches and the measly crop they bear seem to me stunted remnants of a past glory, when periodic fires would sweep through, thinning the canopy and setting the stage for a burst of new growth from the resilient roots of the blueberries, which then prospered in the partial shade of the scattered trees. Thick bark and decay-resistant leaves are common traits of trees that are adapted to periodic fire. Oaks exhibit these traits in Princeton, their leaves persisting on the ground as fuel for fires that no longer come.

The most dramatic example of the distortion caused by fire exclusion that I've witnessed was in a woodlot preserved as part of Bennett Place, a Civil War site in Durham, NC where the war's largest surrender took place. In the past, trains passing close by would throw sparks, causing low-burning fires to sweep through the woodland, promoting the growth of fire-adapted post oaks and shortleaf pine. I like to call these rejuvenating events "mildfires"--the relatively tame wildness of a healthy nature--in contrast to the destructive wildfires we're used to hearing about in the news. The woodland--perhaps more like a savanna--was a favorite place for Duke University botanists to find a rich understory of wildflowers prospering in the open shade. As they remarked on this or that rare species of wildflower, they must have sampled the berries from the broad patches of blueberries that persist there. As trains have become less sparky, and people more fire-averse, the less fire-resistant, fast-growing trees like willow oaks have grown up, while the deepening shade and the accumulation of unburned pine needles have stifled the wildflowers. The once-thriving "fire-climax" ecosystem is begging for a fire that never comes, as the old trees slowly succumb.

Though the exclusion of periodic fire has also made Princeton's woodlands less natural, we can see in the caterpillars' partial munching--some shrubs eaten, some not--the persistence of another aspect of balance in nature, worked out over millenia of coevolution. No species can survive long if it wipes out its food source. Long-term stability thrives on balance. New species introduced from other continents lack these elaborate checks and balances. Stiltgrass smothers large swaths of Princeton's preserves because nothing eats it. Our forests have suffered a series of shocks, from chestnut blight in the 1920s, gypsy moths in the 1970s, and now the emerald ash borer--all from introduced species that lacked the checks and balances that evolve over time.

The common name for our very dramatic caterpillar, "contracted datana," is hardly a common name given how few of us have heard of it, and is merely an adaptation of its latin name, Datana contracta.  Come to think of it, the heads of the caterpillar look a lot like blueberries. Their collective ducking seems to be saying to a hungry predator, "Please move along, no food here!"

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.

With Trees, Looks Can Be Deceiving

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

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

PawPaw Patches Proliferate in Princeton

My friend Stan, who has a knack for collecting and growing out seed of local fruit trees, gave me about twenty pawpaws (Asimina triloba) he grew from local populations of this remarkable native species. Though adapted to the north, the pawpaw bears a fruit reminiscent of mango. Hard to store and ship, the fruit has proven hard to turn into a cash crop, so it remains at the margins of our diets and awareness.

I delivered three to Mountain Lakes, for planting there, then called up my friend and author-of-note Clifford Zink over at Harrison Street Park, to see about starting a pawpaw patch over there.

Last month, we planted three in a swale that receives water from a nearby parking lot--a good urban version of the floodplains that are the pawpaw's preferred habitat.

Around the same time, Bill Sachs gave me some white cedars and hemlocks he'd grown in his backyard. Bill has been leading efforts in town to bring back the native chestnut and butternut. Since white cedars are adapted to swamps, two of them ended up in the Princeton High School ecolab wetland, thanks to environmental science teacher Tim Anderson and his students.

Most of the pawpaws are being saved for planting a pawpaw patch out at the Veblen House site, part of a PawPaw Patch Planting Party, public invited, tentatively scheduled for the first weekend of the new year, El Nino weather permitting.

(Other pawpaw posts can be found by typing pawpaw into the search box at the top of this website.)

Nature Trail: From the All Saints Tract to Herrontown Woods

One of the entryways into the long corridor of preserved land called Princeton Ridge East, including Herrontown Woods, begins on a bikeway that heads up past Princeton Charter School on Bunn Drive. You can enjoy this asphalt bikeway's smoothness, and note that the trees are far enough away that their roots haven't made ridges in the pavement.

For anyone who's curious, a little ways up, across from the water tower, just in from the road, a native chestnut tree is hanging on in deep shade. It was discovered by arborist Bob Wells while he was inventorying Princeton's street trees, and is the only wild native chestnut that we know to exist in town.

Up the hill are the new Copperwood apartments. Though some grand old beech and oak trees were sacrificed to build it, the developer heeded strong resistance from local environmental groups and, rather than spread the allowed units out across the property, he clustered the apartments so that some 20 acres of ridge forest could be preserved.

Look down and to the right from the Copperwood entrance and you'll see a long straight trail extending into the woods. That's the pathway leading through land preserved by the municipality, county and environmental groups, with particularly significant effort put forth by DR Greenway and the Friends of Princeton Open Space.

Just in on the left as you walk down the trail is a large berm that holds back stormwater from Princeton Community Village and Copperwood. There's a slow drama underway on the berm. Woody plants aren't allowed to grow there, so the berm's floristic destiny might be native wildflowers like these late-flowering thoroughworts,

but Chinese bushclover is starting to get a foothold. It was introduced into the U.S. for use in erosion control, and promoted as offering abundant seed for wildlife. But the seeds proved undigestible, and the species has proved extremely invasive, outcompeting native wildflowers and creating inedible monocultures. With a few hours' work, the Chinese bushclover could probably be eliminated from this berm, but management doesn't tend to be proactive, which means the species is likely to increase in number until it's too intimidating to deal with. Where's that Friends of the Berm group when we need them?

Unless you're going to the imagined Friends of the Berm workday to remove Chinese bushclover, continue down the straight and narrow until you encounter one of two trail signs on the left.

These are DR Greenway signs, as part of their followup to preserving the All Saints tract. Down the hill from the preserved property is the All Saints Church itself, which is also home to the Princeton Learning Cooperative, for teens who seek an alternative to a traditional middle or high school education. Our Friends of Herrontown Woods group has partnered with them on nature walks.

Sometimes, it takes a village to maintain even a small sign like this. A resident of Copperwood told our Friends of Herrontown Woods group that he and his wife couldn't find the signs leading to Herrontown Woods. We went looking for the map, found it had disappeared, then told DR Greenway staff, who replaced it. Such is the fabric of connection that keeps Princeton's open space navigable.

Earlier in the fall, I led a walk through the All Saints tract for local digital technology educator John LeMasney and some of his friends. Along with all the beautiful moss-covered boulders of the ridge, we encountered a white oak tree that cleaved but did not break in one of the windstorms of recent years.

Here, Peter Abrams, designer of "B Homes" made of used materials like pallets, and John seek out the right angle for photographing this angled tree.

Where All Saints transitions into Herrontown Woods, we took a look at an umbrella magnolia tree, which may be the only example of this species along the Princeton ridge. The Institute Woods hosts a larger population.

These trails can also be accessed from the Herrontown Woods parking lot, down the street across from the entry to Smoyer Park (where another friend of John's showed off a manual chain saw, which could be useful for invasive shrub removal), and from Journey's End Lane, off of Terhune Road.

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.

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

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.

Salvaging A Hidden Garden in Harrison Street Park

To salvage something of value, we don't need to seek out ships at the bottom of the ocean. Just go to the neighborhood park, where good intentions have left a legacy of blue flowers that, without intervention, would be lost in a sea of weeds.

The wood phlox (Phlox divaricata), a native pollinated by sphinx moths, looks in this photo to be doing great. No threat to be seen.

There's a healthy spread of violets as well.

There's even a native chestnut seedling planted in a deer-proof container, meaning the site is taking part in an effort to bring back one of the great north American tree species.

But step back and you start to see that these thoughtful plantings are beginning to be buffeted by waves of invasives. That white flower is garlic mustard. It's edible and makes a decent pesto if the leaves are picked when young, but in the meantime it is overgrowing the phlox and waging underground chemical warfare against other species.

Here we're looking down on the dense seedlings of mostly garlic mustard that will be next year's dominating wave.

Mugwort, even more of a threat, is advancing from the north.

Burdock (large leaves at top of photo) and curly dock (rosette of smaller leaves close to wall) also shade out the phlox. One could say live and let live, except the longterm consequence, given the Phlox's inability to compete with the invaders, is live and let die.

The good news is that the phlox is showing enough vitality that, with just a little timely intervention, it could continue to flourish in this hidden public garden right next to busy Harrison Street. Since I've never seen wood phlox growing wild in Princeton, this planted garden can show what may have grown in Princeton before development, invasive species, and the deer's intense browsing pressure transformed the landscape.

We can look most anywhere and see a sea of weeds. Here's a chance to sustain a distinctive sea of blue.

Mountain Lakes and Spring's Promise

Beauty is in the eye of the beholder, and gardeners are the soothsayers of beauty. We see promise of future beauty where others may see black planting trays and brown soil. These trays, in the little greenhouse at Mountain Lakes House, are all set to grow native wildflowers for planting in restoration projects nearby.

There's summer beauty, too, sleeping in this raingarden that I designed and FOPOS (Friends of Princeton Open Space) later installed. Some of the raingarden's beauty is in the house's dry basement, which used to flood before we diverted runoff away from the foundation and into the garden. The house is flourishing as a beautiful location for weddings and other events, with the income going to fund open space work in town.

There's sleeping beauty in this field dotted with young trees, just across the driveway from the house.  Many of the trees are bur oaks that were grown in the municipal tree nursery over at Smoyer Park. Bur oaks are more commonly found in the midwest, where they were the keystone species in the extraordinarily rich and diverse oak savannas of pre-colonial America. That ecosystem, lost in a sea of exotic buckthorn and honeysuckle and then pieced back together by botanist Stephen Packard and others, now thrives once more in restored habitats in and around Chicago and other parts of the midwest. I don't know if Princeton will ever open up to the idea of prescribed burns, which play such an important role in maintaining native grasslands and savannas, but one vision of future beauty would be having the meadows of Tusculum grade into a post oak savanna.

There's an extraordinary new film called Inhabit, which documents the permaculture movement. The film was shown at the recent Princeton Environmental Film Festival. Permaculture is a kind of agriculture that emulates wild plant communities in order to grow food for people. A farm emulating the oak savanna might have chestnut trees, with an understory of hazelnuts, and cane fruits and some annual crops in the openings between the scattered trees.

Since hazelnuts are described in the film as having been a common understory species in the oak savanna, and the savannas depended on periodic low-intensity fires sweeping through, then how did the hazelnut survive the fires? This photo of one of the three hazelnut shrubs growing wild at Mountain Lakes shows the many stems generated at the base. The "cool" periodic fires would likely have singed the outer stems but left untouched the stems growing closer to the center of the clone. The oaks are protected by their thick bark.

There was an accidental fire in Mountain Lakes a couple years ago. The area burned makes an interesting study in the typically beneficial effects of periodic controlled burns--a management technique used elsewhere in NJ.

Not sure there's much beauty, present or future, in the riprap stones used to armor the outfall of the lower Mountain Lake, but the dams themselves are beautifully restored.

A botanist can even see beauty in a sewer line right of way, where the opening in the trees allows direct sunlight to reach the ground and foster growth of sedges and wildflowers not common elsewhere in the preserve.

A thick layer of woodchips was laid down on the right of way last year, just down from the lakes, in order to support the heavy equipment needed to install a footbridge.

Two bridges were funded by a grant from the Concordia Foundation, and will provide access to the southwestern corner of Mountain Lakes Preserve.

Note: A nature walk by FOPOS staff will follow this Sunday's 3pm annual meeting of FOPOS at Mountain Lakes House.