Saturday, December 29, 2007

Tulip Trees

Tulip trees reserve their charms for those who seek them out. Demure in all seasons, tulip trees are now discreetly displaying their unusual fruits.

The fruits hang on into the winter even after dispersing their winged seeds into the wind. Spring brings the "tulips", pale yellow blooms tinged with orange and green. Their unassertive colors can blend into the foliage and fail to catch your eye. But when you spot the flowers unexpectedly you are rewarded with the feeling of having discovered a secret.

Once you have seen a tulip tree leaf, you will never mistake it for that of another species. The distinctive shape has been described as that of a maple leaf with its tip cut off. The leaves turn a handsome yellow in the fall.

There is a massive and beautiful tulip tree at 443 Stelle Avenue near the corner of Field.

A tulip tree at 1001 Central Avenue illustrates two of the species' most typical features: a long, straight, slightly tapered trunk with no branches near the ground and a rather narrow crown. The form is distinctive enough that tulip trees can be recognized from a distance even when they are leafless.

970 Hillside Avenue provides another example of a mature tulip tree.

Tulip trees are also called tulip poplars or yellow poplars. In fact, they're neither true poplars nor closely related to the poplars (genus Populus). In the lumberyard, however, tulip tree wood is called poplar and is commonly sold for use as interior trim. The wood is among the lightest in weight of the hardwoods and is not particularly strong.

Tulip trees grow fast and become huge. In a favorable environment they can grow to 200 feet tall with ten foot diameter trunks.(1) Their massive size and weak wood make them susceptible to damage by high winds. For that reason tulip trees are not often used as street trees.

Light and easily worked wood can have advantages, however. Tulip tree trunks were hollowed out by several native American tribes to make canoes. It is said that Daniel Boone took his family and belongings down the Ohio River in a sixty-foot tulip tree canoe, abandoning Kentucky for the Spanish Territory in the late 1700s. (2)

(1) Trees of Pennsylvania and the Northeast, Charles Fergus. Stackpole Books 2002, p. 148.

(2) A Natural History of North American Trees, Donald Culross Peattie. Houghton Mifflin 2007, p. 260.

Copyright Gregory Palermo

Sunday, December 16, 2007

Elm envy

The devastation wrought by Dutch elm disease in the middle of the last century left Americans largely bereft of our favorite street tree. We lost no time in trying to find substitutes that could reproduce the look of American elm and resist Dutch elm disease. Japanese Zelkova, Zelkova serrata, was seized upon as a tree that could replace American elms along roadways.

Zelkova was little known until a few decades ago. It is rare to encounter a mature one. In the last few decades the tree has become a very popular elm substitute. The tree shares the American elm's vase-like habit, but Zelkova's vase is typically squatter. The habit is also stiffer. American elm limbs undulate as they ascend. Not so the limbs of Zelkova, which lacks the elm's sinuous grace.

The tree has a handsome and distinctive bark. The young bark has very prominent lenticels(1), horizontal striations, that are reminiscent of the bark of some cherry trees. Older bark is rough and peeling.

The unusual bark and vase-like habit make this species easily recognizable even when it is leafless.

One peculiarity of Zelkova that has the potential to cause trouble as the tree matures is the density of its branching pattern. An entire forest of limbs emerges from the trunk a short distance above ground level. The Central Avenue tree pictured above illustrates the tremendous branching density. The Putnam Avenue Zelkova pictured below shows how numerous limbs typically originate in a bunch.

One wonders what is going to happen to all those limbs when they get large. You would have to bet that some will be crowded out and will drop to the street. Professor Edward. F. Gilman of the University of Florida (formerly of Rutgers) has drawn attention to this problem. In a presentation at the New Jersey Shade Tree Federation meeting in 2006, Professor Gilman spoke of Zelkova as a special case among shade trees in that it needs careful pruning for the first two or three decades of its life in order to develop a healthy form. Is he being overly pessimistic? Hard to know. There just aren't that many mature Zelkovas around on which to base a judgment. If he is right, the enormous vogue that Zelkova now enjoys is going to lead to large maintenance expenses for the municipalities planting them in great numbers. The only mature Zelkova I know is at 9 Remington Avenue in Edison (off Park Avenue). That tree has a diameter at breast height of about three feet and is quite a beautiful specimen. Pruning history? I haven't a clue.

Another American elm substitute that is growing in popularity, but still a rarity, is lacebark elm, Ulmus parvifolia. Like Zelkova, lacebark elm is resistant to Dutch elm disease. Kathryn Uhrich and Jeff Holmes recently planted two lacebark elms in the curbside strip in front of their house at 1441 Evergreen Avenue. They are the only lacebark elms I know in Plainfield. The peeling bark of this species is exceptionally beautiful. These two elms are an exciting addition to Plainfield's urban forest.

Siberian elm, Ulmus pumila, is yet another elm with resistance to Dutch elm disease. There is an example of this species near the Muhlenberg Hospital Park Avenue parking lot. The first tree on your right as you turn off of Park Avenue onto Laramie is a mature Siberian elm.

Michael Dirr's Manual of Woody Landscape Plants, the Bible for many gardeners, calls this species "one of...the world's worst trees" because of its susceptibility to damage by wind and insects.(2) I think Dirr is exaggerating. I have seen many attractive Siberian elms (not in Plainfield, where it is uncommon), and I find the coarse, chaotic bark quite attractive.

Finally, some people are still planting American elms. Dutch elm disease-resistant varieties include 'Princeton', 'Liberty', and others.
(1) Lenticels are loosely bundled groups of cells that permit gas exchange, allowing the tree to "breathe" through its bark.

(2) Manual of Woody Landscape Plants, fifth edition, Michael A. Dirr, Stipes Publishing 1998, p. 1048.

Copyright Gregory Palermo

Sunday, December 2, 2007

Norway maple

"Norway maples should be banned from the United States." Bill Nierstedt, Plainfield tree guru and head of the City's Planning Division, made this xenophobic comment three years ago. I have waited in vain since then for him to be invited to repeat this hate speech for a national audience on Lou Dobbs' television program. Despairing after three years of ever seeing Bill on television, I decided to reprint his words here.

Bill is too late. The genie is out of the bottle. The horse is out of the barn. Norway maples are here. Norway maples are among the most common street trees in Plainfield. These European imports are perhaps the most numerous street trees in the eastern United States.

It has to be admitted that their bright yellow autumn foliage is quite attractive.

Some varieties have maroon foliage all season.

They're handsome trees. Arthur Plotnik's The Urban Tree Book describes their regular, lollipop form as looking like a tree drawn by a child.(1)

So what's the problem? Norway maples cast an inky shade in which very little can grow. They make a dense network of subsurface roots that quickly suck every bit of moisture from the soil and that lift sidewalks. Any gardener knows that to dig a hole near a Norway maple is to dig a hole in wood. Tight-angle crotches make the trees more susceptible than most to storm damage. Drive around Plainfield after a storm and take note of what kinds of limbs you see blocking the road. Mostly maples, many Norways.

But Norway maples' most egregious offense is that they breed faster than the natives (and I'm sure that it's this fact that most distresses Mr. Nierstedt). Norway maples are the most sucessful reproducers that I know. They put dandelions to shame. In a hospitable habitat like Plainfield, each tree manages to produce thousands of seedlings each year. The seedlings carpet the ground and are difficult to uproot. Those that grow in a lawn eventually succumb to repeated mowing, but what about the rest? They're extremely shade-tolerant and so have no trouble at all growing up in the middle of a mature hedge. They also have no trouble growing up in the middle of a mature forest. They leaf out earlier than most plants and hold their leaves later into the fall, giving them a longer growing season.(2) Norway maples are crowding native species out of our parks and forests.(3)

They're taking over the urban landscape as well. How many hedges have you seen that started out as privet and ended up as maple? Homeowners tire of struggling to uproot the very tenacious maple invaders and instead just shear the maples along with their hedging plants.

What happens if the maple seedlings are left to their own devices for a few years? They make a Norway maple jungle. Such jungles are easily found in Plainfield. The maple jungle pictured below is on Belvidere Avenue near Berkeley.

Don't mix up Norway maples with sugar maples. Although the leaves of the two species are quite similar, the trees are easily distinguished by their bark. Norway maple bark is brownish grey with shallow furrows.

Sugar maple bark is silvery grey and shaggy.

Found: a big, beautiful ginkgo.

955 Woodland Avenue has a mature ginkgo as beautiful as the hacked Netherwood Station ginkgo used to be.(4) It's worth a visit.

Dan Damon sent photographs of a handsome ginkgo in the 900 block of Central Avenue. His photographs are below. Dan made the ultimate ginkgo sacrifice. He got up close and personal with the stinking ginkgo fruits and tracked some of them into his car. For his efforts he got great photographs of fruits that are adapted to fend off even dinosaurs with their odor.

(1) The Urban Tree Book, Arthur Plotnik, Three Rivers Press 2000, p. 95.

(3) To make the threat quite local, Professor Thomas Ombrello of Union County College observes that "There are numerous parks in our area where Norway Maples are displacing the native tree species." The Trees of Union County College, 2nd edition, Thomas M. Ombrello, Union County College 1997, p. 43.
An Overview of Nonindigenous Plant Species in New Jersey, ( published by the state Department of Environmental Protection in 2004, cites Norway maple among 29 "invasive nonindigenous plant species documented to aggressively invade...natural plant communities in New Jersey."
The Invasive Plant Council of New York State includes Norway maple on its list of the "Top 20 Invasive Plants in NYS" (
The Pennsylvania Dept. of Conservation and Natural Resources lists Norway maple among "serious threats to our native ecosystems" (

(4) See April 19 Plainfield Trees post on Ginkgo biloba.

Copyright Gregory Palermo

Sunday, November 18, 2007

Sugar maples

Sad to say, they're in decline. Everyone's favorite tree at this season, sugar maples are declining where we most would like them to be at their best: lining suburban streets. The trees seem most suited to a rural environment. The stresses of suburban living get them down.

What's the problem? Sugar maples are happiest in loose, moist soil. The dry, compacted soils of curbside planting strips disagree with them. More serious problems for sugar maples are urban pollution, road salt, and acid rain. The bottom line: their numbers are falling in this area.

Many writers have commented on the decline of the sugar maple in the suburban northeast. The most poignant account I have seen is in Brian Donahue's book, Reclaiming the Commons. It is Mr. Donahue's peculiar utopian goal that every town should have a community farm. In his book he recounts his experience establishing and running such a farm in a bedroom suburb of Boston. Part of his crop was maple syrup harvested from trees on the suburban streets. As years went by, his maple syrup production dried up because the community's trees were dying off, killed by road salts and automotive pollution:

"During the 1980s sugar maples all over town began disappearing, like the elms half a century before them. By the end of the decade it was as if the maples had never existed --- only a handful remained.... The maples were a casualty of the automotive suburb, and their passing the quest to commute from urban blight to rural sanctuary is self-defeating.... To believe that we can routinely drive great distances to reach an unspoiled landscape full of natural amenities at the end of our journey is a fatal delusion. If we want to live in towns with healthy sugar maples, we simply have to live in them more and drive in and out of them less. We cannot out-commute suburban sprawl."(1)

More problems for sugar maples in our area? Climate change: sugar maples like it cold. The species is often used as the poster-child example of plants that are migrating northward with global warming, as it was in AOL's November 17 report on the latest warming forecast of the Intergovernmental Panel on Climate Change.(2)

How about some good news? Plainfield still has some very fine sugar maples. A particularly nice one is at the Van Wyck Brooks house at 563 West 8th Street.

Other good examples are on Watchung Avenue near Colonial Circle, pictured at the top of the page. Sugar maples near 1326 Prospect Avenue, photographed this afternoon, were still making a very attractive display.

A younger tree, photographed three weeks ago, illustrates the fiery brilliance of sugar maple foliage in bright sun.

Maple syrup anyone? European settlers learned about it from Native Americans, for whom it was the primary sweetener. They concentrated sugar maple sap by freezing it and removing the ice or by placing heated stones in it to cause evaporation of water.(3) It takes about 40 gallons of sap to produce one gallon of maple syrup.

The quintessential maple leaf is the sugar maple leaf. It is the leaf represented on the Canadian flag. It closely resembles the leaf of Norway maple. The two species can be distinguished at a glance by their bark. Sugar maple bark forms shaggy, platelike scales. Norway maple bark is shallowly furrowed.

This year's sugar maple foliage season is near its end on Plainfield's streets. Have a look if you haven't already and enjoy the show.

(1) Reclaiming the Commons, Community Farms and Forests in a New England Town, Brian Donahue, Yale University Press 1999, pp. 166-171.

(3) A Natural History of North American Trees, Donald Culross Peattie, Houghton Mifflin 2007, p. 356.
Copyright Gregory Palermo

Sunday, November 4, 2007

Red: the color of health. Sourwoods, dogwoods, and sweetgums.

Inspired by the "French paradox" of long lifespans in a population with a high-fat diet, some of us hope to stay healthy by drinking plenty of red wine. Many plants adopt a similar strategy by producing red leaf pigments in the fall. The spectacular reds and maroons that light up the autumn landscape are the colors of anthocyanins, a family of antioxidant compounds. These antioxidants protect plants (and us) against chemical injury caused by oxygen, a highly reactive and dangerous molecule.(1)

Some of the best red foliage is visible in Plainfield now. Red maples, sugar maples, and Japanese maples are famous for their red foliage. One of my favorite small trees is sourwood, Oxydendrum arboreum, a native of the southeastern United States that is scattered around Plainfield in small numbers. A fine example is at Watchung Avenue near the corner of Kensington.

The tree highlights its maroon leaves with cream-colored seeds.

One of the many charms of our native dogwood is its beautiful maroon fall foliage.

Sweetgums, maligned for their production of difficult-to-rake gumballs, more than make up for whatever maintenance problems they cause with a panoply of red fall colors.

Some sweetgums have autumn foliage in yellow tones.

Deciduous plants don't just passively lose their leaves in the fall. They make elaborate preparations for winter. Red antioxidant coloration is part of that preparation. Green leaves are colored by chlorophyll, the molecule that allows plants to capture the energy of sunlight. When the leaves are shed, plants don't allow the chlorophyll to go to waste. They break it down and move the breakdown products to the roots, where they are stored over the winter. With their energy-generating machinery moving into storage, plants are in a vulnerable state. As they lose their chlorophyll, the leaves of some plants gain protective anthocyanins and reddish colors. The latest scientific thinking about why the leaves of those plants turn red in the fall is that additional antioxidative protection in dying leaves permits orderly breakdown and withdrawal of the chlorophyll before the leaves fall. This subject is nicely summarized by Colin Tudge in his recent book, The Tree.(2)

Some autumn leaves develop yellowish tints. Where do those colors come from? Yellow autumn leaf pigments are generally chemicals that have been present all during the growing season and that are unmasked by the absence of chlorophyll. Yellow and orange carotenoids play a role in photosynthesis. They are also antioxidants.(3)

(1) Blueberries are touted as good sources of anthocyanins. A widely cited study found that elderly rats had an improved sense of balance after being fed large quantities of blueberries for weeks.

(2) Colin Tudge, The Tree, A Natural History of What Trees Are, How They Live, and Why They Matter, Crown Publishers, 2006, pp. 357-359. The author points out that new spring leaves and shoots, also particularly vulnerable to injury, have a red tinge in many plants.

(3) Beta-carotene has been a widely used dietary supplement. I suspect that its popularity fell off after scientific studies seemed to indicate that taking it did not offer the hoped-for cardiovascular benefits. Better, it seems, to get your antioxidants by eating plants, not pills.

Copyright Gregory Palermo

Sunday, October 21, 2007

Poised to inherit the earth: red maples

Red maples are poised to inherit the earth. The sad facts of this change in the fortunes of red maples were laid out by William K. Stevens in a beautifully written article in the New York Times in 1999.(1) As Mr. Stevens tells the story, red maples, aided and abetted by humans, are taking over the forests of the eastern Unites States, displacing oaks as the dominant species.

Plainfield has numerous red maples (Acer rubrum) as street trees. They're most easily spotted in the spring when their early-blooming bright red flowers catch your eye as you pass.

Red maples are also noticeable in the fall, as their foliage turns red or orange before dropping. The trees can be distinguished easily from the other maples likely to be seen in the area. Unlike sugar or Norway maples, red maple leaves usually have only three lobes, not five. Another clue is their red color: red maple leafstalks, buds, samaras (winged seed cases), and flowers all have some red color. Colorful spring flowers and autumn leaves make for an attractive tree. Red maples' biggest problem is a tendency to split in strong winds, a drawback that it shares with several other maple species.

They are also susceptible to heart rot, leading to wind-snapped trunks.(2)

How are people helping red maples usurp the dominant role in eastern forests? In a multitude of ways. European settlers started the process by cutting down all but about two percent of the eastern forests' trees to make farms. Farming moved westward, and eastern farms were largely left to revert to forest by the early twentieth century. Red maples, although usually inhabitants of wet soils, were very adaptable opportunists.(3) They quickly inserted themselves into the newly open spaces.

Oaks and hickories have thick bark that protects them against forest fires. Thin-skinned red maples are much more likely to be killed to the ground by fires. Modern humans almost completely suppressed forest fires, stripping oaks and hickories of their natural advantage over red maples. Fire suppression had a second effect on the tree balance. Fires created open spaces ideal for light-loving oak seedlings. Maple seedlings are much more shade-tolerant than oaks and thrive in the darker environment created by fire suppression.
We did another favor for red maples by making the landscape very friendly to deer. Vastly expanded deer populations suppress oak numbers by eating huge quantities of acorns.

Yet another boon to red maples was our importation of gypsy moths, prodigious eaters of oak leaves. We also introduced Dutch elm disease and chestnut blight, dealing a knockout blow to other red maple competitors. Finally, there is evidence that red maples are more tolerant of acid rain than most tree species. Man's best friend? Dog. Red maple's best friend? Man.

More on chestnuts: Plainfield has a native American!

Robin Gates wrote that we have an American chestnut in Plainfield. You don't have to trek to Monmouth County to see one. Bill Santoriello planted one at 946 Madison Avenue when he owned that property in 1992. The tree was obtained from The American Chestnut Foundation and is now eight or nine inches in diameter at breast height.

Although the tree will eventually succumb to chestnut blight, it might live a long time. A stand of 200 native chestnut trees about 80 years of age was recently discovered in Georgia (4)

The Plainfield tree recently produced a large crop of chestnuts.

Click on photograph to enlarge.

(1) William K. Stevens, Eastern Forests Change Color as Red Maples Proliferate, New York Times, October 22, 1999.

(2) Charles Fergus, Trees of Pennsylvania and the Northeast, Stackpole Books 2002, p. 199.

(3) "Red maple can probably thrive on a wider range of soil types, textures, moisture, pH, and elevation than any other forest species in North America." Russell S. Walters and Harry S. Yawney, Red Maple, in Silvics of North America, U.S. Forest Service,

(4) The American Chestnut Foundation

Copyright Gregory Palermo

Sunday, October 7, 2007

Wish-list trees: tupelo and goldenrain tree

I drive by two of my favorite trees each day on the way to my office. But not in Plainfield. The trees are in Edison. I keep hoping I'll see some in Plainfield. No luck yet.

Tupelo, Nyssa sylvatica, is an American native. The species is clearly native to Edison, to judge from the numbers of them there.

The tree's best season is now, when its glossy green leaves turn crimson before falling. Tupelo is capable of growing to over 100 feet in height but is typically seen as a much smaller tree. Tupelos favor moist ground. The name tupelo comes from the native American Creek language, meaning swamp tree. Its Latin name means water nymph of the woods. The tree is also known as black gum, sour gum, and pepperidge. Pepperidge farm cookies and breads are named for an ancient tupelo growing on the Fairfield Connecticut farm where they were first baked.

The wood of the tupelo has interbraided and cross-woven fibers that make it basically impossible to split(1). Useless for most purposes, the wood is good for the handles of tools that get heavy use. The island of Martha's Vineyard has its own local name for the tree that derives from the wood's use in tools and the island's maritime trade history. Islanders call it "beetlebung tree". Why beetlebung? The wood was so resistant to abuse that it could be used not only for the bungs that plugged barrels, but also for the beetles (mallets) that were used to pound the bungs into place.(2)

Tupelo's foliage is beautiful spring, summer, and fall. The small, oval leaves are glossy and thick; they look as though they should be evergreen. The berries have a very high fat content, making them attractive to a large variety of birds.(3) Why don't we have tupelos in Plainfield? Their only disadvantage is a tap root that makes them a bit difficult to transplant. A minor flaw, I think.

Golden rain tree, Koelreuteria paniculata, is a small Oriental tree that makes a spectacular show of yellow flowers in summer.

Its flowers are followed by papery lantern-like seed capsules, which have an appeal of their own.

Goldenrain trees are the perfect size to fit under overhead utility wires. We should have some of these beautiful little trees in Plainfield.

(1) Donald Culross Peattie, A Natural History of North American Trees, Houghton Mifflin 2007, p. 383.

(2) "Beetle" is related etymologically to "beat" and "abut".

(3) Charles Fergus, Trees of Pennsylvania and the Northeast, Stackpole Books 2002, p.220.

Copyright Gregory Palermo

Sunday, September 23, 2007


Has even one American in 50 seen an American chestnut? We know the tree as wood, not as a tree. American chestnuts supplied countless Plainfield and other American houses of the early twentieth century with beautifully grained lumber for decorative woodwork. The trees are a distant memory. They were the most common tree in eastern American forests until they were largely wiped out by chestnut blight.

When I thought I saw an American chestnut at 1479 West Fourth Street last weekend, I brought my car to a screeching halt and leaped out to get a closer look. Wrong! A Chinese chestnut, the American chestnut's closest mimic. Any species of true chestnut is a rare bird around here. The West Fourth Street Chinese chestnut is the only chestnut I've seen in Plainfield. It's a beautiful tree, and it's quite easy to spot in this season because of its numerous large nuts and its bright green sawtoothed leaves.

Chinese chestnuts are apparently the culprits that introduced chestnut blight when they were imported into this country. The Chinese species, Castanea mollissima, is little bothered by the fungal blight that is so devastating to the American chestnut, Castanea dentata.

The American Chestnut Foundation is trying to breed the disease-resistance of Chinese chestnuts into the American species to bring back American chestnuts from the brink of extinction. Their breeding program has hybridized the two species to select for blight resistance in the offspring. Resistant progeny are being "backcrossed" with American chestnuts over several generations to progressively reduce the Chinese genetic element. The goal is an American chestnut that has Chinese genes for blight resistance. Plainfield attorney Victor King, an American Chestnut Foundation member, has three of the hybrid chestnuts growing on his property in New Hampshire and tells me that they are doing well.

If you want to see an American chestnut, you probably have to leave town. Stump sprouts, seedlings, and saplings are mostly what is left of American chestnuts. I went to see some in Monmouth County's Hartshorne Woods yesterday. Traipsing around in the rain, I found several young trees. American chestnuts have large, sawtoothed leaves that are thin and papery. Chinese chestnut leaves are thick and waxy. American chestnuts have hairless red-brown twigs with sharp buds that project out from the stem at a 45 degree angle. Chinese chestnut twigs are hairy and tan to pea-green. Their buds are rounded and hug the twig.(1)

The trees with sawtoothed leaves on East Second Street between Park and Watchung Avenues are not chestnuts. The leaves are chestnut-like, but the trees are oaks.

At a quick glance there is very little about these trees to make you think oak. Except acorns! In this season the trees have littered the ground with large numbers of big, heavily fringed acorns. Sawtooth oaks provide the most extreme example of oak leaves with bristle tips, one of the defining features of the red oak group. But that subject is for another time.

Note sawtooth oak's extravagantly fringed acorn caps. Click on the photograph to enlarge.

(1) The American Chestnut Foundation's excellent pictorial guide to speciating chestnuts:

Copyright Gregory Palermo