Trouble For Princeton's Trees

To inoculate you for the news carried in this post, I'd like to point out that wishful thinking is not the same as hope. In fact, to the extent that it postpones action, wishful thinking can be thought of as the enemy of hope. Bad news is much more easily accepted if we feel confident in our capacity to work together as a community to respond.

Princeton has a real challenge ahead if it is to keep its protective canopy of trees in coming decades. There are the losses in recent years due to storms like Hurricane Sandy, the ongoing attrition as some pin oaks and red oaks succumb to Bacterial Leaf Scorch, and then there is the gathering storm just to our west of the emerald ash borer. Through a recently completed tree inventory, Princeton can now look at the numbers, and they don't add up--the number of trees likely to be lost dwarfs the number of trees being planted.

Doing the Math

Here are the numbers, rounded off for easier math, as presented by Bob Wells of Morris Arboretum, who directed the inventory and integrated it with an earlier survey of borough trees done by Jim Consolloy. These are only the trees growing in the street right of ways. Trees in parks, preserves, and on private property are not included. Of Princeton's 19,000 street trees, 3000 are in poor condition--unlikely to live beyond the next five years. Another 6000 are in fair condition, with an estimated life expectancy of 5-15 years. Even those trees in good condition are threatened by a growing collection of invading insects and diseases, along with the increasing weather extremes associated with climate change. For instance, some of Princeton's 1400 pin oaks and red oaks will continue to be lost to Bacterial Leaf Scorch.

Compare those numbers with the current replacement rate. Princeton purchases and plants about 60 trees each year along the streets. Its tree crew takes down about 250 trees each year in parks and along streets. The numbers offered up by the tree inventory estimates the annual loss of street trees to be a minimum of 600. By this math, we will be losing ten trees for every one being planted. And this doesn't even take into account the imminent arrival of the Emerald Ash Borer.

http://www.tinleypark.org/index.aspx?nid=648

Emerald = Less Green

Perhaps most worrisome is the looming threat to Princeton's most common tree, the ash. We can expect to lose most of our 2200 white and green ash trees along the streets in coming years, plus the tens of thousands in our woodlands. The culprit is the emerald ash borer (EAB), an insect that hitch-hiked to southeastern Michigan in wooden packing crates from China, then proliferated to kill 50,000 trees before anyone knew what it was. Since its identification in 2002, EAB has been radiating out across the midwest, killing tens of millions of trees, including a relentless spread eastward through Ohio and Pennsylvania to the border with New Jersey. A map at this link shows New Jersey essentially surrounded by infestations in bordering states.

As chance would have it, the original EAB infestation occurred just north of Ann Arbor, MI, where I used to live. The city of 100,000 had to spend $5.8 million removing 10,000 trees. Interestingly, ash continue to sprout in the woodlands there, and can grow to 6 inch diameter, but the chances of their growing to maturity are slim.

Princeton has dealt with threats to trees in the past. A bacterium called Bacillus thuringiensis (BT) has been used to reduce the impact of gypsy moths. According to Greg O'Neil, Princeton's arborist, the wooly adelgid's attack on our eastern hemlocks was slowed down by pesticide, after which the pest appears to have "cycled through", allowing many hemlocks to survive.

There is, however, no known control for emerald ash borer other than individually treating each tree, and even then the results are mixed. As an added complication, Imidacloprid, the most frequently mentioned systemic insecticide for protecting ash trees, may be contributing to the decline of honey bees.

What To Do

The sooner we acknowledge the depths of the challenge we face, the more proactive we can be, and the better the prognosis for Princeton's tree canopy. There are a number of actions that can be taken. Treatment for ash trees that are particularly cherished is best undertaken before the emerald ash borer arrives. To better spread the work of removal over a number of years, some of the younger or less healthy ash trees can be taken down and replaced with another species before the invasion hits. The municipality should at least be planning for the extra staff needs and the seven figure expense coming down the pike.

The big question is how to replace so many trees with a limited budget. The more gaps in the street canopy, the more pavement is exposed to the sun, which through the "heat island effect" causes the town to be hotter than it need be in the summer. At $200 a piece, new trees aren't cheap, and then there's the planting and followup care to insure they survive.

One approach I'm exploring, as a member of the Princeton Shade Tree Commission, is transplanting "volunteer" trees that sprout in people's yards. Some species are more appropriate than others, and determining where to plant them along the street requires some guidance. Perhaps we can come up with a guide, and motivated neighbors could take initiative in their neighborhood to identify gaps and work with willing homeowners to get trees planted in an optimal place and manner along the street. Given the infinite reasons that can be summoned for inaction, such an approach will only work if people see how their own needs can be met by participating in the collective endeavor of shading our streets.

For me, the hope lies in the growth force and the natural affinity people have for trees. It's remarkable how quickly the red oak in this photo, which sprouted on its own in my next door neighbor's yard not that many years ago, has grown large enough to cast much-needed shade on our driveway.

Neighbors a couple doors down have transplanted volunteer trees to key spots in their yard--to shade the house, provide habitat for birds, and provide buffer from the street. After just a few years, they are robust young trees--a white oak, pin oak, American elm and tulip poplar. Another friend is growing a pawpaw and a fig in a sunny spot in their backyard--going for food rather than shade.

Each kind of tree has its strengths and potential drawbacks and vulnerabilities, but after years in which Princeton's landscape was dominated by mature trees, it's refreshing to see young ones coming on the scene, filling the voids, reaching for the sun.

Related to this, the opening reception for an art exhibit entitled "The Fallen and Unfallen: Trees in Peril" is Nov. 1 at the DR Greenway, 5:30 to 7:30. More info here. With paintings and photographs, it celebrates trees while also identifying some of the threats they face, in little snippets of info like this one.

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.

September Nature Vignettes

 Encounters with nature and sustainability around Princeton in September.

One of my favorite corners in Princeton is near the middle school, at Guyot and Ewing. It's a small enclave, a triangle of sense, where the yards and the roofs of houses actually perform work, growing food and gathering energy. On one side is a small house with a small yard that the owner has turned into an orchard and vineyard, as might be more often encountered in Italy. 

Nearby is a house whose south-facing roof has been completely covered with solar panels for 20 years. 

When a house was torn down recently at the corner, I feared it would be replaced with something huge and unattractive, 

but instead, a one-story house with extra thick insulated walls and solar panels and interesting design is taking form. It was a real surprise to see a one-story house being replaced with another one-story house that is sensitive to the history of the site and seeking to fit in, while showing off a modern design that seeks to minimize energy consumption.

They even have a sign on the fence describing the project and what was there back in Princeton's agrarian era. 

Blooming along the fenceline next to the house are sunflowers and autumn clematis vine. Gorgeous as they are, thankfully generating color at a time when most flowers are spent, they are best not planted in a garden unless where the spread of their roots is limited by a house or pavement. Otherwise, given abundant sun to power their aggressively spreading roots, they will take over your garden.

Another common encounter in September is with late-flowering thoroughwort, which spreads not by roots but by seed. It can be weedy but also lovely and even elegant at times, and is great for pollinators. I couldn't get myself to pull this one out in our backyard, even though it has completely taken over a garden path.

At the Barden in Herrontown Woods, they are so plentiful that we don't feel too bad pulling out the ones that lean over the pathways.

The fight against invasive species has the side benefit of taking me to areas of a nature preserve where I wouldn't otherwise go. Recently, it led me to a patch of native diversity in Herrotown Woods that I hadn't noticed before.

Here is obedient plant, 

New York ironweed, 

and the post-flowering look of water hemlock. 

One of my favorite garden plants this time of year is stonecrop "Autumn Joy." 

A sedum, its disks of flowers go through a gradual enrichment of color from green to pink to deepening shades of red, then finally chocolate. Nonnative but noninvasive, it has the added benefit of being popular with pollinators. 

Pawpaw trees are becoming more common in Princeton. The patches planted in Herrontown Woods have yet to bear, but this one in my backyard reflects a growing interest in this unusual species native to the north yet with a tropical taste.

Native persimmons, likely once common in Princeton but often shaded out by larger trees in recent decades, are an attractive smaller tree that might actually bear edible fruit if you happen to get a female and harvest it just at the right time.

If the drought hasn't made the berries too dry, these blackhaw berries could make for some good picking after they darken. Blackhaw viburnum, Viburnum prunifolium, is the most common native viburnum in our woodlands.

Less generating of anticipation are the fruits of a female ginkgo tree, encountered growing near the Princeton Junction train station. The fruits have such an unappealing smell that people try to avoid planting female trees. 

Among inedible fruits, I call this the incredible shrinking pokeweed, because it initially grew to be seven feet tall--way too big to grow along a busy street. So I cut it down midsummer and thought that was that, only to have it sprout back as a smaller version of itself. You could try this technique with a number of perennial native wildflowers that get too tall for people's taste. Cut them down partway through the summer, then let them grow back in a miniature form. 

Though it dies down to the ground each year like a perennial wildflower, pokeweed looks more like a miniature tree, and in fact it has a close relative in Argentina. The ombu grows to the size of a large tree, yet lacks xylem. 

This shrub, too, needs to be cut back. It's an oak-leafed hydrangea I planted long ago in a little raingarden at the front of the Whole Earth Center. The landlord the store leases from must have a new landscape firm taking care of the grounds, because I stopped by recently to find that my native shrubs have been trimmed to look like bowling balls. Funny to see a native shrub and wildflower planting getting the bowling ball treatment. I'll have to take some loppers to restore light to the window next time I stop by to buy some beets or delicious bread.

Sometimes, frequently in fact, I find myself wishing I wasn't right. Take this ash tree for instance, planted by the people who landscaped the new parking lot that Westminster Choir College built about ten years ago. I told them they needed to remove the ash trees they had just planted. The emerald ash borers are coming, and the trees won't survive. They left the trees in. The trees survived longer than I expected, but are finally succumbing. 

Actually, if you were trying to make Princeton sustainable, you might want to "farm" Princeton with smaller, short-lived trees that provide shade but are less expensive to take down. The above ground portions could be periodically harvested as a local energy source, and the roots left in the ground would sequester carbon. Trees are a source of solar energy, since they draw their carbon not from underground but from the atmosphere all around them. Thus, no net increase in atmospheric carbon from their combustion.

The landscaping for the parking lot also called for a raingarden to be planted here in this hollow. After being planted, the young river birch trees soon began to wither for lack of water. I assumed they would die, and that the raingarden would be poorly maintained and ultimately be mowed down. I was only half right. The river birch trees survived.

Here's what looks like a bright white flower that isn't. The white is the puffy seeds that give the plant its name. The flower seems not to open but remain in what looks like a bud stage. It's pilewort, a native weed that can reach seven feet tall.

Finally, a grass encountered in fields and local rights of way. When its flowers open and display their golden anthers, this native member of the tallgrass prairies can be eye-catching. Indian grass, Sorghastrum nutans, reminds me of the midwest prairies I used to help manage, and a time long ago when prairie openings were common in the east as well.

The Evolution of the Front Lawn in Ann Arbor, MI

Back when I was writing and performing climate theater, it was a very useful exercise to view things like the earth or the economy as characters. Upon reflecting on what sort of character a front lawn might be, I realized that the expanse of mowed grass is much like a trophy wife for the House. Expected to be well manicured, passive and forever young, the front lawn serves no other purpose than to present a flattering view of the House to the public. In return for its submissiveness, the front lawn is allowed, and in fact expected, to remain perpetually idle. Any shift away from bland formality, such as a wildflower meadow or, heaven forbid, a vegetable garden, would be unbecoming and steal attention away from the House. It seemed to me the front lawn could benefit from a good turf therapist who could help her sort through how she ended up in such a one-way relationship, and from that developed a monologue called Turf Therapy. 

It's easy to knock suburban culture's striving for a sterile deep green conformity, and the chemical dependency and noxious lawn equipment that keeps it propped up. But most homeowners find themselves completely unprepared to own land, and the myriad kinds of plants that grow upon it. No surprise, then, that people try to turn the outdoors into as simple a landscape as possible, essentially an extension of the indoors. A lawn is the equivalent of a wall-to-wall carpet. 

In our era, the expansion of the suburban lawn has coincided with a shrinkage in knowledge of plants. Each generation sprouts more distant from ancestors who farmed or foraged. And how many schools teach children to identify even the most common trees? 

It's a brave homeowner, then, who dares take a shovel to the front lawn, bucking conformity to plant something more colorful, beneficial, and interesting. Usually, the change is wrought incrementally, expanding flowerbeds a little at a time. 

While most plantings tend to hug the edges and stick close to the house, in this yard a Salvia is boldly asserting itself right out in the middle of the yard.

Just down this street, which happens to be called Easy Street, someone dug a raingarden that catches water piped to it from the roof. They used the dirt dug out of the hole to build a berm on the downhill side, expanding the hole's capacity. The wildflowers feed the pollinators while the signs feed passersby with ideas, like Public Power, in which a town takes ownership of its electricity and moves rapidly towards 100% renewable energy.

A neighbor further down has converted even more of the yard to raingarden, and added a sign from the local watershed association: "Rain Garden: Improving wildlife habitat and water quality in the Huron River one garden at a time." This is a nice sentiment that all too often remains on the fringe, but in this neighborhood it has caught on.

Next door is a vegetable garden in the front yard. It's starting to look like the trophy wife has decided to pursue a life of her own. Any House with an ego is going to be really upset.

This homeowner, a friend of mine named Jeannine, has nurtured a burr oak savanna habitat in her front yard, with an understory of trilliums, plus black cohosh in its full mid-summer bloom. The House? Well, it's back there somewhere, having to accept that yards like to express themselves and have meaningful lives, too. 

Interestingly, some of her bur oaks are getting tall enough to start interfering with the solar panels on their garage. She has started managing her front yard forest, removing larger trees while keeping smaller ones not tall enough to shade the panels. It's a way of having your trees and panels, too. Each tree removed leaves a legacy of roots--a network of carbon consumed from the air and injected into the ground.

Even in more upscale neighborhoods, where homeowners can afford to hire landscapers, many yards are cared for by crews that carefully weed the wildflower meadows, displacing the noisy custodial crews that "mow, blow, and go." What a pleasure to bicycle through a lovely neighborhood with colorful, botanically interesting yards and a delicious quiet. Machines to suppress vegetation are replaced by skilled intervention to steer vegetation. All week in Ann Arbor, the neighborhoods were remarkably quiet. I looked online for information about bans on leaf blowers, and could only find a ban on 2-cycle lawn equipment in the city's downtown, passed in 2019.

The shift from lawn to meadow in many yards was surely inspired in part by the work of Jeannine Palms, who with her preschool kids, neighbors and town staff have carved native wet meadows into what had been a vast expanse of turfgrass in nearby Buhr Park. 

Their meadows have many of the same wildflowers we have in Princeton, with some differences. The photo shows gray-headed coneflower, which is close in appearance to our cutleaf coneflower. And they have additional kinds of Silphium (rosinweed, prairie dock, compass plant), and a grass called smooth cordgrass. 

More recently, Jeannine has led a volunteer effort to shift even more of the park away from turfgrass, in this case to create a food forest packed with grapes, apples, pears, elderberry, pawpaw, currants, raspberries, strawberries, fennel, and a "three sisters" planting of corn, beans and squash. 

Here's an effort to grow sweet potatoes, not only for the tubers but also for the leaves, which are delicious. Fabric is spread on the ground to suppress weeds, and fencing suspended above to deter the deer. 

The story of this heroic transformation is told in a sign posted next to the first wet meadows. In the process, they have brought diverse, edible life back to the land and the neighborhood. 

My Parents' Garden

One thing I did on May 8, the first Mothers' Day since my mother passed at the age of 94 earlier this year, is to pull garlic mustard at Mountain Lakes Preserve. The logic of this is rooted in my parents' backyard, in the '70s in Ann Arbor. They had just bought an old Tudor house, previously owned by a mathematician. That first spring, yellow primrose popped up along the garden paths, with swaths of pulmonaria, mayapples, solomons seal, bloodroot and trillium grading into a small woods. There was little difference between the cultivated and wild areas, the gardens being little more than a steering of nature's already fortuitous and ornamental energies, with a few gentle introductions like primrose and pulmonaria thrown in.

That order, which seemed timeless at first, began to slowly unravel year to year. A patriarch elm, its graceful arms spreading in a protective arc over the center of the garden, succumbed to Dutch Elm Disease. Myrtle, wisteria and bishop's weed (snow on the mountain) began their relentless expansions. Hours were spent in hand-to-root combat, as rock walls and less aggressive species came under ongoing threat of being engulfed by a monotonous, weedy tide. Garlic mustard slipped into the mix somehow, at first seeming ornamental enough to leave, then turning into brown skeletons later in the summer, flinging its seeds about before I thought to react.

The fight to save a valued balance was not against exotics, but instead against the aggressive plants, the preponderance of which happened to be exotic species introduced into the garden by chance or with the best of intentions. The wildflowers continued to bloom along the path edges, and one year a pawpaw sprouted mysteriously in one of the beds, eventually bearing tropical-tasting fruit. But the beauty and serendipity that make a garden a joy were under constant threat from a subset of plants with imperialistic tendencies.

That garden taught me more than could have been guessed about the forces that tilt the world towards imbalance, and the work required to counter them.

Some Flowering Trees and Shrubs in Mid-May

A whole lot of white, and a little red right now. Here's fringe tree

and pagoda dogwood

Red buckeye is a small tree that makes a big show here and there on residential streets. I've only seen it growing wild along a back road in the North Carolina coastal plain.

pawpaw hanging promisingly

This fragrant snowbell (Styrax obassia), was planted by Bob Wells behind Veblen House in Herrontown Woods.

And across the street from me, a horse chestnut puts on a dazzling display, with flowering, towering black locusts adding lofty blooms behind.

Osage-Orange and the Missing Megafauna

Looks like somebody didn't finish their Thanksgiving dinner. In fact, I don't think they even showed up at the table.

This Osage-Orange, a native tree named after an Indian tribe, grows next to Princeton Pike. Indians reportedly prized their wood for bows, and colonists used them as living fences. As a species, they don't get around much anymore, mostly because the megafauna with the teeth and digestive system to eat their formidable fruit, and transport their seeds, went extinct in America more than 10,000 years ago. The megafaunas' extinction conspicuously follows the arrival of Homo sapiens to this continent.

The giants that once roamed our piece of the earth--among them mastodons, woolly mammoths, giant sloths, horses--not only transported the seeds but served other ecological services, transporting nutrients from floodplains up to higher ground and maintaining clearings with their massive appetites.

To the osage-orange, add the honey locust, Kentucky coffeetree, and pawpaw as rarely occurring species that might have once been more common if their seed dispersers hadn't disappeared.

Next Thanksgiving, for something different, consider inviting some genetically reconstituted megafauna to dinner, and don't forget the Osage-Orange.

Among many sources for more reading:
http://www.americanforests.org/magazine/article/trees-that-miss-the-mammoths/
http://www.asecular.com/forests/megafauna.htm
http://www.highlandssanctuary.org/NaturalHistory/Kamama/hall.article.htm

Leaves -- A Love Story

Leaves are easiest to love during their "fifteen days of fame" in the fall. But though a true love of leaves may first take hold in the fall, maybe in a particularly colorful leaf picked up by a child on the way to school, it ultimately deepens and matures to include the less showy times that leaves go through, from an obscurity of green up above to an obscurity of brown underfoot, to a slow return to the air and ground from which they came. A love of leaves is so richly rewarded, by the oxygen they give in abundance, the shade, the transpirational, transformational cooling in the summer, the remembered exhilaration of raking and leaping into leafpiles, and the fabulous pulse of surface area and food leaves give to the ground each fall to insulate and feed the life of the soil that in turn sustains all life. Such abundant gratitude they show for the ongoing gift we give without even thinking, "a breath to build a leaf on." Leaves, after all, are built to a great extent from the carbon that we and other animals exhale.

Here are some photos collected this fall:

A sweetgum tree on Princeton University campus across from McCarter Theater. Of course, you expect leaves in such a setting to be above average,

but even the wild ones can put on something of a show, as in this field of sweetgum seedlings in a field next to Snowden Lane,

and even rival the cultivateds. This photo was taken only with the intent of showing variation in size of leaves that fell near Veblen House. The car's hatchback windshield was the closest horizontal surface. Only when looking at the photo later on did I see that nature, ever the artist, was composing the photo as much as I.

This photo of a native witchhazel planted next to a house on Linden Lane led to the unceremonious end of a phone conversation, as my cellphone battery died moments later.

In Herrontown Woods, witch hazels were more the color of these backyard pawpaw leaves. Shade can mute the brilliance of color, and sometimes alter the color itself.

The leaves of mapleleaf Viburnum vary year to year and place to place along the Princeton Ridge.

Wasn't expecting a musclewood to be so colorful. This is a lovely understory tree of Princeton's forests, but my neighbor has one flourishing in her front yard, close to a busy street. (Carpinus caroliniana)

Virginia creeper hanging from a blackhaw Viburnum. Lots of sun, lots of color.

The oakleaf hydrangia and stonecrop "autumn joy" can be a fine combo, their colors slowly shifting through the fall. The stonecrop isn't native, but stays where it's planted, and gives pollinators a fine late-summer dinner plate of nectar.

And lastly, another form of autumn joy--my older daughter when she was discovering the pleasure of leaves while growing up in Durham, NC. The child within us can make that love and delight last a lifetime.