XVII.6 November + December 2010
Page: 20
Digital Citation

BETWEEN THE LINESThe taxonomy of the invisible

Liz Danzico

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A spring 2010 app competition, NYC BigApps, brought together designers and developers to show how the city of New York could improve the way it provides information to its citizens. One of the 11 winning apps, "Trees Near You," now helps users learn about the more than 500,000 trees that live on city sidewalks. For any area of New York City, one can discover tree species and calculate the environmental benefits that the trees provide, using publicly available tree census data. One of the most prevalent trees in the city, however, isn't included [1].

Look out of any New York window, and you're likely to see one, but you'd be hardpressed to identify it. The reason: ailanthus altissima, or the "tree of heaven"—made famous by Betty Smith's 1943 book, A Tree Grows in Brooklyn—hasn't technically been planted by anyone. And because its placement was unintentional, it isn't counted in street-tree inventories. Still, it grows, and at a staggering rate of five feet per year and up to 49 feet tall. It's these sorts of plants, and their smaller relatives, that we refer to as "weeds." Yet to one Harvard biologist and those counting around him, they're just 'spontaneous."

back to top  Roots in Nomenclature

Peter del Tredici, a senior research scientist at the Arnold Arboretum of Harvard University and lecturer in landscape architecture at the Harvard Graduate School of Design, argues the wildlife that surrounds us every day often has an image problem—it goes unnoticed, unattended, and unvalued. "There is no denying the fact that many—if not most—of the plants...suffer from image problems associated with the label 'weeds,' or, to use a more recent term, 'invasive species.' From the plant's perspective, 'invasiveness' is just another word for successful reproduction—the ultimate goal of all organisms, including humans.... The term is a value judgment that humans apply to plants we do not like, not a biological characteristic" [2].

If it's true that more than half the world's people organize themselves in cities, then it's our responsibility to understand and pay attention to the wild and unmanaged plants that grow up all around us. In the United States and other wealthy countries, more than 80 percent of people live in cities and suburbs. In these areas, wild plants are often ignored. They're "crypto-forests," as Dan Hill describes them: "Weed patches in which the earliest emergent traces of a thicket can be found; clusters of trees growing semi-feral on the edges of railroad yards; forgotten courtyards sprouting with random saplings unplanted by any hand: these are all crypto-forests" [3]. These urban spaces are a mix of the built, the wild, the human, and the cultivated. And as designers and service designers, we must approach all aspects of the system—the wild included—as equal contributors.

To understand better how to do so, we can look to the way in which "invasive species" has been defined. "'Weed' not a category of nature but a human construct, a defect of our perception," Michael Pollan points out [4]. On one hand, if weeds have had an image and perception problem, they are then "any plant growing in the wrong place." Then, on the other hand, they are any plant "considered to be a nuisance in human-made settings and that grows and reproduces aggressively" [5]. But a stronger position comes from Weeds of the West: "a plant that interferes with management objectives for a given area of land at a given point in time" [6].

Given these definitions, weeds have also become a business problem.

back to top  Stemming from Early Days

Perhaps it's the way we've been taught. I thought back to "weeding," a good-hearted but somewhat totalitarian weekend activity in my parents' garden, one I frequently attempted to escape. On Saturday mornings, my parents would announce "weeding orders" for the four children, and we were to set out, in the hot sun, the driving rain, the falling leaves of autumn, and attack. They saw no boundaries. Indeed, there was a stone wall around our property, but should there be weeds crawling past that limit, if natural forces had besieged it, we should follow suit. In our town, these weeds were not seen as heroes, braving the pavement and cracks of the sidewalk. So we, from week to week, were not taught to marvel at the dandelion or clover that sprang forth, spontaneously, without human design or planning, but rather to uproot them.

"I consider 'weed' to be a politically incorrect term," del Tredici says. "There is no biological definition of the term 'weed.' It's really a value judgment" [7]. What could we have achieved differently in the way we designed our urban landscapes had we thought about designing with different values? Further, what if we took a different approach to thinking about what's native to a city? Nothing is native to an urban environment. The modern city is new as a habitat, he argues, one that provides livable spaces that can be harsh, polluted, and inhospitable. If we looked at the assortment of spontaneous growth differently, del Tredici positions, we might have a respect for it. Delicate and hearty living things in the urban landscape, thriving. With little design by us, these plants provide greenery, clean air, shade, food, and habitat. It's time, he suggests, we learned to embrace them—to stop thinking of them only as weeds to uproot, and start considering what they have to offer [8]. And while it's clearly his intention for us to make these considerations for spontaneous growth, it's not such a stretch for us to extend our thinking to wild spaces in other areas of design.

back to top  Growing Up

Spontaneous urban vegetation is easier to consider kindly when you examine it this way. I unknowingly pass lamb's quarter on the south end of my local park, then purchase it for several dollars at the north end of that same park at the farmers market. And while the common reed is considered an invasive in North America, in the European range it's considered to be in ecological crisis.

"Most people tend to interpret the presence of spontaneous urban vegetation in their neighborhood as a visible manifestation of dereliction and neglect while viewing the same plants growing in a suburban or rural context as 'wildflowers' (think about the beautiful combination of chicory and Queen Anne's lace along the roadside in July and August). Clearly the context in which a plant exists has everything to do with how people feel about it" [8]. The aesthetics of ecologically functional, spontaneous urban landscapes often leave something to be desired. Is there a way to balance spontaneity with people's need to be in a tidy environment?

back to top  Editing Spontaneity

The question of aesthetics is more complex in urban environments. There, urban landscapes are dominated by weeds and a pursuit to remove them, rather than a landscape whose design is dictated by removal of trees and shrubs. Such "landscape editing" can dictate the attitude of a place, much like Philip Johnson chose the placement of each tree, and even particular branches, on the property of his 47-acre Glass House property in New Canaan, CT. Each no different in intent, perhaps, from our pursuit to omit what we think are "needless words" or trim unnecessary features. Yet in nature, are they natural?

There are landscape concepts that take advantage of spontaneity—those such as the "freedom lawn"—plans that result from the interaction of naturally occurring plant life and the selective effect of lawn mowing; or the "spontaneous roof," a modification of the better-known "green roof." Less spontaneous, but more unexpected, is the "urban rooftop farm," growing in popularity in urban environments as a way of providing fresh fruits and vegetables at a small scale [8]. Del Tredici refers to some of these practices as less about planting and more about editing, since the plants are allowed to grow naturally and weeding is minimal, aimed primarily at undesirables that may crowd out other plants.

back to top  Organization of the Neglected

Del Tredici's basic goal in organizing the 222 plants that spontaneously grow in the urban environment of the northeastern United States—a task close to any information architect's heart—is to foster an appreciation for the role plants play in making our cities more livable. Whether these wild plants were present before we altered our environment, were brought in by us, or arrived on their own, they are everywhere and traditionally invisible to us. With his recent book, Wild Urban Plants of the Northeast: A Field Guide, del Tredici has created a taxonomy for spontaneous vegetation to make them recognizable to urban dwellers.

Whether by ferns, horsetails, conifers, woody dicots, herbaceous dicots, or by monocots (the reference guide is organized according to the major botanical categories, the highest level being the taxonomic group), one can navigate the guide to understand the organization, although photos of weeds are oddly familiar when perusing the pages.

Take a step further and we can nurture the neglected into something more curated. In urban ecology the concept of a "cosmopolitan urban meadow" emerges, in which urban meadows are planned by humans but based on recommended weeds. They're selected on the following criteria:

  • Erosion-control value
  • Stress value
  • Aesthetic value
  • Wildlife value
  • Economic value

The intent for these sustainable urban meadows is temporary—to be used on a vacant lot, for instance—until something more permanent is decided in its stead. Vacant lots are transformed into urban prairies with less weeding and upkeep by locals.

Likewise, in the built environment, a similar yet intended hijacking is taking place, but this time by the architect, Stéphane Malka, and its location, the Arche de la Défense in Paris.

"A pocket of active resistance installs itself within the building in the form of a modular complex offering an alternative and militant lifestyle. The project bears with it a permanent insurrection and unites all malcontents, whether refugees, stateless persons, dissidents, outcasts, or utopians. Referring to the notion of concretion, its construction principle allows for expansion tailored to the effervescence of this spontaneous community. It bases itself on the existing fabric using walkways grafted on to the lifts and a system of scaffolding leaning against the rear facade. A guerrilla architecture project that aims to hijack the great arch of fraternity" [9].

More permanent perhaps is the concept of alternative art galleries that appear, like the one that inserts itself under the tracks of the BarbèsRochechouart metro station in Paris. Once the viewer is on the street, "this off Bunker reveals itself as an exhibition space that is elongated and generous, offering a multiplicity of views from different levels. The gallery responds to the challenge of addressing neglected spaces, generating a singular place, a spontaneous cultural space divergent from the restrained exhibition spaces of Paris" [10].

back to top  Context in Unlikely Places

In 2010, Partners & Spade published a book, I Think I Can, I Think I Can, of 16 photos all taken with an iPhone camera around New York City. It chronicles weeds pushing their way past pavement, concrete, cracks, and other unlikely places. A photo essay on possibilities on what seems impossible, but what we now know is simply an image problem. They are, after all, just successful. It's all a matter of context.

back to top  References

1. NYC BigApps;

2. Del Tredici, P. Wild Urban Plants of the Northeast: A Field Guide. Ithaca, NY: Comstock Publishing Assoc., 2010.

3. "Crypto-Forestry and the Return of the Repressed" BLDG BLOG, 20 June 2010;

4. Pollan. M. "Weeds Are Us," New York Times Magazine, 5 November 1989;

5. Janick, J. Horticultural Science (3rd ed.). San Francisco: W.H. Freeman, 1979.

6. Wikipedia entry;

7. Humpries, C. "This is Not a Weed." Boston Globe, 23 May 2010;

8. Higgins, A. "Harvard Biologist Comes to the Defense of the Much Reviled Tree of Heaven." Washington Post, 14 June 2010;

9. Self Defense;

10. Bunker Gallery;

back to top  Author

Liz Danzico is equal parts designer, educator, and editor. She is chair and cofounder of the MFA in Interaction Design Program at the School of Visual Arts. She is an independent consultant in New York, on the strategic board for Rosenfeld Media, and is on the board of Design Ignites Change. In the past, Danzico directed experience strategy for AIGA and the information architecture teams at Barnes & and Razorfish New York. She lectures widely and writes for

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