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.)

Lose a Tiger(lily), Gain a Paw(paw)

"Come see our tiger lilies!", I was told at a party recently. Naturalists get this sort of invitation now and then. I was a bit skeptical that they were tiger lilies, though, because there was mention of spreading,

and the only tiger lilies I've come across in Princeton are the ones in this photo, behind Conte's. Nevertheless, I took them up on the invitation--my interest piqued by the owner's enthusiasm about these lilies.

Sure enough, they proved to be daylilies, a step above the humble, unimproved orange found in abundance in my yard and many others, but daylilies nonetheless.

Now, I didn't really want to be a bearer of bad news, or even not-so-bad news, since a day lily is still a lily, whose blooming is no less worthy of the owner's enthusiasm for lacking a tiger in the name. People's relationships with plants should not be taken lightly. The plant names that inhabit my brain in abundance tend to take up only the briefest of residencies in the minds of most others, falling away like leaves in a late October breeze.

So when a plant name lodges firmly and resonantly in someone's mind and heart, it's hard to point out that this plant that has come to be known so emphatically as a tiger lily is in fact a daylily. The flower itself is far from plain as day, but "day" can't compete with "tiger" for affection. Which day is the daylily named for? It could be a good day or a bad day, sunny or gloomy, we really don't know. There's no hint of wildness in a day. A day is a mere vessel to be filled with meaning, not a gloriously fearsome beast stalking your yard, fortunately in the benign form of a flower. As I weighed my options, a homeowner's connection to a plant, facilitated by a colorful name, hung in the balance. What to do?

Long a slave to truth, I sought at least to soften the news, by saying that all lilies that grow in Princeton with that classic orange color really should be deserving of the tiger lily name.

After all, with tigers all aprowl on campus, guarding various entryways, the Princeton University Tigers on one side of Nassau Street, Little Tigers on the other, and tiger stripes dominating the color schemes in parades and giftshops, doesn't tigerdom eventually seep into all things and people who reside here long enough? A certain fierceness, perhaps, lurking beneath the civilized demeanor. If nothing else, it manifests in a Princetonian's capacity to leap into the breach and spout copious, tenacious opinions at town hall meetings.

The owners seemed to take the news well enough. If daylilies they are, then daylilies it is, from here on out, though I could tell a bit of magic had fallen away from their front yard. We continued to the backyard, which had that minimally managed grow-what-will look. I was tempted, because of the ground made wet by a very active sump pump--the house having been built on what was likely once a tributary of Harry's Brook--to recommend various of the floodplain flowers that would prosper there, but resisted. There was something soulful and relaxing in this yard that wasn't trying to be anything other than what it is, shaded by Norway Maples and backed by a thick stand of bamboo that obscured the condos just beyond the fence.

I looked around and saw the usual, a pokeweed here, a rose of sharon there, Japanese honeysuckle growing on the fence, and was going to go back to conversation when I happened to look up and saw, what's this? Pawpaws? The northern growing tropical fruit that many of us covet, many have planted, and many must now wait years for any chance of a crop. And here it was, a mature tree loaded with fruit, prospering unbeknownst to anyone in a grow-what-will garden.

I pointed it out, proud of my find, hoping it might make amends for the loss of a tiger lily. Surely, the taste on the tongue of the word "tiger" cannot compare to the lush, yellow, mango-like pulp of a pawpaw. Only later did I realize that I had taken away a tiger, but left them at least with a paw or two. Who knows, maybe it's the distant descendant of the lost pawpaw patch of Harry's Brook, where sabertooth tigers stalked the megafauna of yester ice age.

Addendum: If you dare to walk right up to a tiger lily, you will see the spots on its petals and small black bulblets in the upper axils. The bulblets, if memory serves, can be plucked and planted, to make little tigers. 

Other lilies hereabouts are the towering native Turk's Cap lilies at Morven Gardens, 

with their whorled leaves,

and another, the most truly wild but also the shortest, flying below the deers' radar out at the Mercer Meadows prairie restoration on Cold Soil Road. 

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.

Local PawPaws Ripe

For anyone who hasn't tried pawpaw--our northern representative of a largely tropical family of fruits in the Annonaceae--the Whole Earth Center has some in stock from a local supplier. The harvest only lasts a couple weeks each year, according to one employee. Pawpaws have a short shelf life, and bruise easily, which has long hampered efforts to market them in anything beyond a small scale, local fashion.

I bought one and shared it with my daughter, who had never had one. She said it tastes like a combination of mango and kiwi. Delicious.

You can type "pawpaw" into the search box at the top of this blog to find a couple previous posts on the subject.

Sustainable PawPaw Liberation Service

As someone highly empathic towards plants, I woke up today sensing that something was amiss. Somewhere, a native pawpaw was being shaded out by a Norway maple. Now, I like Norway, and I like maples, but a Norway maple tends to sprout unasked along the fencelines of our fair town, then cast its over-the-top stifling shade upon all hapless plantlife that, through no fault of its own, happens to be growing nearby. Many plants suffer in silence. In fact, just about all of them do, if they happen to be suffering, and it's up to those of us bestowed with special powers, caring, and knowledge to act for their welfare. The situation is all the more dire when a pawpaw is not getting enough light to make flowers and bear that delicious tropical-tasting fruit.

As the founder of the Sustainable PawPaw Liberation Service, it's my job and perhaps solemn duty to rescue pawpaws in distress. A deep commitment to botanical justice and increased pawpaw productivity moves me at times like this to finally stop posing in front of my garage with my pawpaw liberation saw,

and put some mettle to the pedal. Useful tip: Riding while holding something in one hand is probably not a good idea, but if your hat looks alot like Lancelot's, or at least you're holding something that looks alot like a lance, you'll find that car drivers suddenly start showing some respect.

I arrived on the scene without a second to lose, although if I'd waited a week it probably wouldn't have made much difference. Just as I suspected, a friend's pawpaw was being heavily shaded by a Norway maple. The pawpaw's endearingly obovate leaves were literally, or at least laterally, crying out for sunshine.

Elsewhere in the yard, its faithful companion pawpaw, long liberated, kissed by sunshine and now thirty feet high, had borne most nobly a thousand blooms this spring just past, yet for lack of a companion to cross--pollinate with, it had not one fruit to show for it. Clearly, action was needed so that this fine upstanding couple might share their pollen and bear most heavily many a pawpaw in years to come.

A few deft strokes of the pawpaw liberation saw were all that was needed to, well, at least get the lowest maple branch out of the way. You can see a little gap in the canopy where the sun can shine through. A higher branch will require even more chivalry, and a good ladder.

Though logistics prevented a fully accomplished mission, the intervention may still bear fruit.

Lonely PawPaw Seeks Cross-Pollination

Round about Mother's Day, my friend Karla received this email: "Lonely apple tree seeks similar for discreet short-term relationship. Afternoons preferred." Just in case there was any misunderstanding, some explanatory text was added: "My tree is blooming, for the first time; is yours? If so, can our trees make a date? Warm regards."

As it happened, her husband Steven was headed that very day to South Brunswick on a related mission, in search of pollen to satisfy the fruiting needs of another kind of fruit tree, the solitary pawpaw planted in their backyard some years ago that was now in full bloom. Though it had sprouted an additional trunk, it was still lonely, genetically speaking, and unlikely to set fruit unless visited by pollen from another pawpaw patch.

Thrust into the role of pollinator, Steven found himself at a distinct disadvantage. He had neither the wings to search the greater Princeton area for other pawpaw trees, nor sufficient olfactory apparatus to detect the subtle carrion-like odor pawpaw flowers use to attract pollinating flies. And since Google Maps does not (yet) provide directions to New Jersey's pawpaw patches, the search for prospective pawpaw mates required considerable research savvy. Even upon arrival at the best prospect he could find, the orchards at Rutgers, he still required the kindness of strangers to find the pawpaws amongst all the other fruit trees in the no-doubt vast plantings at Cook College.

This sort of matchmaking is becoming more common as the local food movement, perhaps abetted by backyards made sunnier by tree-toppling storms in recent years, prompts the planting of solitary fruit trees in cloistered backyards--peaches, apples, cherries, figs, persimmons, pears, and the occasional pawpaw--all with uncertain prospects for leading a healthy, promiscuous life of cross-pollination.

For those who know pawpaws only from the childhood lyric about a "pawpaw patch", they happen to be a native understory tree in the Annonaceae--a family of mostly tropical species. One relative of pawpaw grown by the Incas is touted as perhaps "the greatest fruit on the planet", with a taste combining mango and banana. Pawpaw, adapted to the north, offers a chance to grow tropical tastes in cold climes. Though delicious, its shelflife is short, which has thus far limited the pawpaw's commercial potential.

Thanks to the internet, I now know that the "way down yonder in the pawpaw patch" phrase that I've been carrying around in memory all these years comes from a boyscout song. I did not personally reach the status of boyscout, having earned my bobcat, wolf and bear badges in cubscouts only to lose momentum during a leadership void in that critical transition from cub to boyscout. The transition is called webelos, which stands for "we'll be loyal" scouts, a molting process that not everyone successfully completes.

If I had, I might have learned the complete lyrics for Pawpaw Patch, and known that "way down yonder in the pawpaw patch" answers the musical question "Where oh where oh where is Susie?" It matters where Susie is because she happens to be the "queen of Hawaii", which goes with the pawpaw's tropical family roots. If you ever go to Hawaii, you may encounter some of pawpaw's relatives, like the ylang ylang, soursop, and sugar apple. However, according to the song, you needn't go way down to Hawaii, because Susie will teach you to hulu way down yonder in the nearest pawpaw patch. If not completely distracted by Susie's hulu tutorials, the astute boyscout will note that "way down" and "patch" are descriptively correct, because the pawpaw tends to grow in rich bottomlands, and forms clones from its spreading roots.

There's another lingering pawpaw-related mystery knocking around in my memories. In my parents' Michigan backyard in the pre-internet 70s, a pawpaw sprang up spontaneously one year, grew into a patchlet of several stems, and after a few years began bearing flowers and a few fruit the size of a small mango. Where the pawpaw came from is a mystery, as was its capacity to bear fruit, because there was no known patch nearby, and the seeds looked much too large to navigate a bird's digestive tract. We didn't ask questions, however, because they were delicious. A bit of pollination assist with a cue tip may have helped with yield one year, which the raccoons and squirrels were grateful for.

Steven's recent research, empowered by the internet era, has delved far more deeply into the sexuality of a pawpaw. Way up yonder in this pawpaw post is a picture that Steven sent me of two pawpaw flowers, the green one not yet having acquired that lovely burgundy hue that flies are supposed to mistake for dead meat.

If a pawpaw flower were able to speak to its sexuality, it would say something like "I was female before I was male." Here to the left is a male flower, which is really a female flower a few days later. Looking closely, you can see a subtle difference. There are now yellow (male) anthers surrounding the green dot in the center (female stigma). The logic is that the anthers on any particular flower open up as the stigma is closing down, thereby preventing a flower from pollinating itself.

But that logic suggests that a tree with flowers in different phases could in fact pollinate itself, with pollen from one flower spreading to the next, and make fruit without importing pollen from elsewhere.

Still, the available information suggests that it helps to have cross pollination from one pawpaw patch to another, and that human-assisted pollination is often needed to make up for a lack of interest among the local flies.

Next year, Steven won't have to travel to South Brunswick in search of a "house of reputed pawpaws", because by chance I found a fine potential mate in the backyard of another friend, behind the Jewish center just a quarter mile away. It's a splendid specimen, thirty feet high, sporting perhaps a thousand flowers.

But pawpaw growers shouldn't have to depend on chance discovery. There needs to be an internet dating service for fruit trees. Sometimes it takes a village, or at least a good network.

Update, June 9: Just met a neighbor named Joe who has replaced the lawn in his side yard with four varieties of pawpaw and a lot of mulch. He says that wild pawpaws are common in Maryland, that raccoons and squirrels may be repelled by the bad-tasting skin of the fruit, and that it's easy to emerge from wild pawpaw patch with large buckets of fruit. I did not ask about any encounters with Susie, or if Marylanders are more adept at doing the hulu.


Some interesting links:

http://apiosinstitute.org/asimina-triloba-pawpaw

http://www.hort.purdue.edu/ext/ho-220.pdf

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

Homage to the Next Generation of Trees

One fairly rare sighting, both in Princeton's woodlands and parks and along streets, is a young tree. The great Mercer Oak that was finally blown down after 300 years of life was replaced in 2000 with an offspring, but how about all the other trees that have been lost in recent years, and will be lost if the predictions of Princeton's recently completed tree inventory prove correct? Perhaps we've gotten out of the habit of planting trees, having long been spoiled by their abundance.

This blog takes all sides on trees, praising one tree, ruing another, finding tranquility in a deep forest or opportunity in the sun-filled opening a fallen tree leaves behind, and ever thankful for how they give both in life and death.

This post offers examples of young trees growing in auspicious locations, and all the wonderful work they are already doing.

First, I'd like to thank a neighbor for letting a volunteer red oak grow in a perfect spot to shade my driveway and pickup truck. They probably haven't even noticed it, but I do. Seems like just the other day it was a little sprig peeking over the fence.

And thanks to the folks, too, who paid for a tree to be planted in Potts Park to celebrate the birth of their son. We chose the spot carefully, wanting it to eventually shade the play equipment through the summer, but not be out in the field where it might intersect with a kid running after a ball. Many swings and play structures around the world are not being allowed to live up to their full potential, abandoned by kids when they overheat in summer for lack of a tree.

Another red maple, though perhaps better to have been planted on the house side of the sidewalk, is beginning to fill one of the many gaps along our streets. We need many more trees like this one to keep Princeton's pavement from baking in the summer. The more this tree shades and transpires, the less pedestrians will perspire.

Hard to believe that not long ago this pin oak and American elm were little two foot volunteer seedlings my neighbors transplanted to their front yard. Their faith in the growth force in modest saplings, and the remarkable way time has of passing, is quickly yielding a visual buffer and afternoon shade for their house.

This backyard tulip poplar was another volunteer transplanted to a spot well away from the house.

This young backyard white oak is doing a good imitation of Mercer Oak Jr. over at Princeton Battlefield. Just beyond the fence, in Potts Park, a grove of white oaks planted by the town has matured into a favorite spot for picnics and birthday parties.

Another friend has started a pawpaw patch in their "back 40",

and a fig tree bearing delicious figs in a protected spot next to the driveway.

Though ginkgoes don't support wildlife the way native trees do (a recent article in the NY Times reports that only a few insects feed on ginkgo, while an oak serves up food for more than 500 insect species), these stilty varieties are shading the way along an improbably narrow space over at the Princeton Healthcare Center.

I like to think that the proximity of young trees, with their dynamic growth happening at our level, puts us better in touch with an aspirational energy that can feed our own. When I hear Copland's Appalachian Spring, I think of young landscapes--prairies and early successional stages. In addition to the mature beauty of a forest, we need among us these renewing landscapes, these fresh beginnings, to feed our spirit.

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.

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.