Leaf Head: A New Yorker Learns to Look at Trees

I remember my first tinge of curiosity. It was a warm day, late enough in summer for a few acorns to have fallen, and I was in Fort Greene, standing around with some friends underneath what was probably a pin oak. I looked down at my feet and had a realization. Not only did I not know where acorns come from; I had never even thought about it. That afternoon, I went to a bookstore and picked up New York City Trees: A Field Guide for the Metropolitan Area, a slim green paperback that fit in my back pocket. A few days later, Quercus was the first genus I could identify on sight.

For years, I took the book everywhere. In my down time, I looked up the leaves I had seen during the day, or read tree trivia. Baseball bats, I learned, are made of the New York native white ash, a fact that I recall involuntarily when I hear the crack of a well-hit drive. I taught myself to identify the four species of linden that grow in the New York — silver, bigleaf, American, and littleleaf. Piece by piece, the canopy’s green haze began to arrange itself into distinctive patterns.

Oak was a good place to start. The leaves have lobes that are easy to spot, and acorns are unmistakable. By autumn I didn’t even have to look up from the sidewalk to know that one was growing nearby. There’s a wide range of individual oak species within the genus, too. Chestnut oak, English oak, scarlet oak, Eastern white oak, Northern red oak, laurel oak, willow oak, swamp white oak, black oak, pin oak, post oak, and turkey oak can all be found in the city.

Oak took me back to the beginning of New York’s modern arboreal history. An original New Yorker, it was right here alongside beech, tulip, maple, chestnut, elm, and hickory when the largest city in the United States was still just an archipelago of dense forests. If you visit Prospect Park in Brooklyn, or Inwood Hill Park at the northern tip of Manhattan, or Van Cortlandt Park in the Bronx, you can still see some of the original growth — woods that have been regenerating naturally, relatively undisturbed, since before the colonial period. For the most part, though, the native forests have been paved over. It’s almost impossible now to really understand what the area looked like in the 1600s, but some estimate that acre-for-acre, it hosted more plant species than Yosemite National Park does today. In Mannahatta, a popular book about the city’s natural history, ecologist Eric Sanderson and cartographer Markley Boyer took a shot at imagining the land as it was then. Their computer-generated images show a Manhattan island full of woods, ponds, and streams — a thriving natural ecosystem.

Unsurprisingly, the first efforts to manage those forests consisted mostly in destroying them. Even before Henry Hudson sailed down the river that now bears his name, the native Lenape were systematically clearing woodland to make room for farms and hunting grounds. In the 17th century, as the Dutch began to expand their territory, the trees began to disappear rapidly. Peter Stuyvesant, the director of the West India Company’s fortress in lower Manhattan, established settlements that would later become neighborhoods such as Bedford-Stuyvesant, Elmhurst, and Harlem. The new communities needed streets, buildings, firewood, farmland, and pastures, all of which required deforestation on a massive scale. By the end of the century, the landscape was entirely transformed.

The more I learned, the more mysterious the city felt. Streets I had walked down a hundred times were unfamiliar, teeming with gangly, alien life forms. One tree in particular, a ginkgo outside my parents’ apartment building, caught my attention. Its branches didn’t splinter off into the thick, rounded crown like those of other trees. Instead, they glided up in playful curves, each one bent out like a shaggy tentacle. Its leaf, unlike any other I had seen, grew in the shape of a small fan. I had passed it every day on my way to school, but now it seemed bizarre.

Ginkgo biloba, I learned, is an anomaly in the tree world. The lone surviving species not only in its genus, but in its family, order, class, and division, it has no relatives in the plant kingdom. It is a living fossil, with ancestors in the geological records dating back over 200 million years. In western countries, the species was itself believed extinct until the 1690s, when a German botanist travelling in Japan came across a live stand. It was found to be resistant to disease and insects, while tolerant of smog and salt runoff. Today, ginkgo is one of the city’s most successful street trees — an arboreal variation on the American immigrant story.

New York’s ginkgoes date back to the 1700s, an era that saw some pushback to the mass deforestation that preceded it. Wealthy landowners began to decorate their estates with ornamental trees, importing species from all over the world. Bowling Green, now the oldest park in New York, was established in 1733. A future New York Lieutenant Governor named James De Lancey even planted a fruit orchard in lower Manhattan.

When the plan for Manhattan’s grid was announced in 1811, however, almost no space was allocated for trees or parks. A surge in construction, combined with an enormous wave of immigration (the city’s population increased tenfold between 1800 and 1850), all but erased the planting efforts of the 18th century. De Lancey’s orchard was paved over and renamed Orchard Street (which today intersects his own namesake, Delancey Street, on the Lower East Side). The estates disappeared. In the place of trees, smokestacks and chimneys rose up across the city.

The results were predictably catastrophic for the quality of life in New York. The streets became filthy; the air filled with smoke. Those who could afford it went upstate on weekends, escaping to resorts in the Catskills, while other retreated to Green-Wood Cemetery in Brooklyn, which became, by 1860, the nation’s second-busiest tourist attraction (Niagara Falls held the top spot). Out of that discontent, a fervent public desire for parks arose, and the city initiated an era of extensive planting. This was the age of Central Park (est. 1857), Prospect Park (1867), Van Cortlandt Park, and Pelham Bay Park (both 1888).

If the city owes its greatest parks to the 19th century, its most popular street tree, the London plane, rose to prominence later. It is unmistakable: its bark a smooth, creamy white, with large pieces peeling off to reveal slight variations in color. Some sections look almost green, while others have a faded purple tinge. Platanus x acerifolia in Latin, it is a hybrid of the oriental plane and the American sycamore. Bryant Park, Cadman Plaza, Grand Army Plaza, City Hall Park, and Riverside Park — as well as countless playgrounds and smaller parks across the city — are full of these majestic trees.

Like much of New York’s present-day physical appearance, its London planes can be traced back to the inclinations of a single man. Robert Moses adored them. On his instruction, the Department of Parks put them into the ground just about everywhere. The London plane had a knack for city living: tolerant of both air pollution and heavy pruning, the tree’s roots do well in the compressed, crowded soil below New York’s sidewalks. “Unlike the arboreal primadonnas,” the Parks Department declared in 1948, “it can take abuse.”

Ever since the first sections of Central Park were opened to the public in 1858, trees have been pouring into built New York. Spurred on by the success of Olmsted’s project, the city rushed to acquire as much of the remaining estate land as it could. By 1900, Forest Park in Queens, Riverside Park in Manhattan, Van Cortlandt and Pelham Bay Parks in the Bronx, and Prospect Park in Brooklyn had all been completed. From 1934 to 1960, during Moses’ tenure as Parks Commissioner, the city doubled its park acreage. Under the Bloomberg Administration, the New York Restoration Project and the city set out to plant a million new trees, a goal that was reached in 2015.

The product of that work — New York’s vast, diverse forest — requires enormous amounts of specialized care. Not only must the Department of Parks and Recreation address the particular needs of over 150 species, but it must do so in an environment that fights back. Sidewalks and curbs deprive street trees of rainwater. Skyscrapers rob them of sunlight. In large quantities, the rock salt and calcium chloride used to remove ice and snow from pavement can poison them. The city’s subterranean infrastructure poses its own set of problems: as early as 1913, park managers were describing the “increased aggression of subways, sidewalks, vaults, sewers, [and] electrical conduits.” Civil engineers, undoubtedly, felt the same way about the trees.

I noticed trees struggling against the city everywhere. Trees growing in the shadows of large buildings bloomed later, I saw, than their neighbors across the street. Others had roots that pushed up through the ground, shattering pavement. In Williamsburg, I observed a telephone wire snagged in the limbs of a ginkgo — a wrestling match that would play out, inch-by-inch, over several years.

One winter, with no deciduous trees to look at, I noticed a dearth of evergreens on the streets — a mild surprise considering how common pine is across Long Island and New Jersey. As early as 1902, parks managers were calling for their removal, citing an intolerance for New York’s smoky air. Later, as the skies cleared, they were excluded for different reasons. Their cones, in addition to making a mess, are hard enough to do some damage to whatever they fall on — a matter of particular concern for street parking. The 1908 release of the Ford Model T virtually guaranteed that cone-bearing trees would be passed over by city planners for generations.

There are other notable absences. In 1935, poplars and silver maples were banned for their tendency to upend pavement and invade sewers with their roots. Later the female ginkgo, whose seeds emit a vomit-like smell in the fall, was retired. New York’s elms — once ubiquitous on roadsides across the city — were virtually eliminated by Dutch elm disease, a fungal infection that ravaged the nation during the 1930s. The rare survivors, like the stand of American elms in Central Park (the world’s largest), and the rickety, wire-rigged Camperdown elm in Prospect Park, are small-time celebrities among tree watchers.

Walking on Macon Street in Bedford-Stuyvesant one day, I saw something odd. Every tree for a half-block between Throop and Tompkins Avenues had been painted white around its base. A man who was gardening in the soil under one of the trees filled me in. The block had a mosquito problem in the summer. Painting the trunks was a trick, he explained, for keeping insects away.

In 1902, Central Park’s managers touched on the problem of bugs, describing a “fecundity… so enormous that often whole sections of the parks are devastated by their ravages in a short time.” In 1934, the Japanese beetle and the “dreaded chestnut blight” were of particular note. Ten years later the fall webworm “harassed citizens and devoured trees.” An insect called the elm bark beetle, which bores through the surface, was responsible for transmitting Dutch elm from tree to tree.

I had never seen a painted tree in a city park. When I got home, I looked up tree painting and found there was no consensus how the repellent worked. According to one writer, a chemical in the paint irritated the bugs. Another insisted that the white color reflected light and lowered the temperature around the base of the trunk. My favorite explanation came from a comment in a gardening forum: “Bugs climbing up from the ground are better seen by birds and other bug eaters if they are on a white background. Bugs know this too.” When I asked the gardener on Macon Street if he’d painted all the trees, he shook his head. Just the one, he told me. I’d have to ask his neighbors about the rest.

All kinds of New Yorkers, I’ve realized, are crazy about trees. Enthusiasts hang trunks with homemade signs denoting the species, or urging dog walkers to keep clear of the root bed. During a long bike ride across the city, a friend and I once stopped on Randall’s Island to watch an old man who was shuffling along the edge of the path, grazing on fruit from the nearby trees. When we asked him what he was eating, his face lit up: “Mulberry!” He held up a few berries and nodded at the branches. His parents, he explained, had been silk farmers in China. They’d raised these trees behind his childhood home to feed their silkworms. He watched as we pulled a few off and put them in our mouths. They were mild, and a little sour. I gave him a thumbs up, and we rode off smiling. Still, I couldn’t help but feel a tinge of envy. His relationship to those trees was a piece of his family history — something innate and personal. Everything I knew came from books.

In 2005, long before I had looked down at an acorn and up at an oak, more than a thousand New Yorkers took time out of their schedules to map, identify, and measure trees for the Parks Department’s decennial Street Tree Census. During the most recent count, in 2015, the number of volunteers more than doubled. Most people, I’m aware, learn early on that acorns come from oak trees. I was in my twenties by the time I thought to ask. I was late to the game — a tourist in my own city, blocking foot traffic to gawk at leaves and consult my guidebook. Relative to New York’s trees, though, we’re all newcomers. In 2009, residents of Douglaston, Queens cut down a rotting white oak estimated to be around 600 years old. It was growing before Christopher Columbus was born.