Few ideas are as loaded -- and as controversial -- as that
of “weed.” Combine this familiar term
with the equally problematic term urban, and surely, confusion is guaranteed to
reign.
However Zachary Falck, an environmental historian, acts as
a knowledgeable and confident guide into this troubled intellectual
territory. He has written the well
documented and very readable Weeds: An
Environmental History of Metropolitan America, published by the University
of Pittsburgh Press in 2010.
My slowness in discovering this book is no indication of its
importance. In fact, I recommend it to
denizens and friends of the Baltimore Ecosystem Study LTER as a compelling
exploration of the interface of the social and the biological through the lens
of plants that are themselves vessels of complex connotation.
What's In A Name?
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| Chickory, photo by Erica Tauzer. |
Weeds have many other names, and each name collects its
own
bouquet of connotations, biases, and values.
This group of plants can be called colonizers, ruderals, and volunteers;
invaders, pioneers, or any number of more technical terms. Falck introduces some intentionally novel
terms in order to avoid, or perhaps highlight, some of the assumptions so
deeply, yet silently, embedded in the term weeds. Perhaps Falck’s primary goal in the book is
to make readers look for the hidden social and cultural assumptions that so often
accompany the reference to weeds.
One reason I am so impressed with the job Falck does in
examining weeds as a window onto urban systems, with both the changes and
consistency of the thinking about nature in urban systems, is that my roots as
an ecological scientist trace back to studies of the germination behavior of the
seeds of common ragweed, Ambrosia artemisiifolia.
These studies, conducted in the lab of Drs. Jerry and Carol
Baskin at the University of Kentucky, showed that common ragweed was
extraordinarily well adapted to colonizing physically disturbed soils, and its dormant
seeds could persist for years buried in the soil between episodes of such disturbance. Yet, the adult plant demands high levels of
light and other resources, and as plant communities changed after disturbance,
ragweed was displaced by other species that could use lower levels of light and
soil resources. Jerry Baskin and I (Pickett and Baskin 1973) concluded that the best management strategy for ragweed was to leave it
alone. Soil treatments designed to
uproot common ragweed would in fact promote a new crop the next year. Falck reviews the history of ragweed control
efforts in some major American cities, and notes their consistent failure. That failure was almost guaranteed by ignorance
of the biology of the species and the
mismatch between that biology and the management strategies employed. But there are other riches in this book.
Weeds As Social Signifier
Weeds have been addressed as a biological phenomenon, of
course, but Falck richly documents how they have also been used as a social
signifier. On the one hand, weeds stand
for elements, both social and biological, that are deemed suitable for
eradication or exclusion from American cities.
Hence, disfavored ethnic and racial groups, immigrants from other
countries of from rural regions of the US, and persons who engage in what
others sometimes or nearly universally define as harmful behaviors, are labeled
as weeds. On the other hand, weediness
stands for an admirable ability to flourish in polluted, hazardous, or
otherwise unfavorable conditions. This
description has been applied to plants, animals, and, again, to different
social groups.
The troubling thing about all these assumptions is that they
are so rarely rigorously questioned. The
term weed is so familiar and so intuitive that people seem to use it without
question or examination.
Falck, however, shows that the richness of conceptual,
demographic, political, and even biological ideas that “weed” can refer to is
immense. Even in legal uses -- in which
one hopes for clarity -- social values, biology, social class, power, and knowledge
are confounded and intertwined. For
example, the aesthetic of the park-like, shared American front lawn thwarts the
establishment of meadows or prairie as a landscaping approach. But such limits seem most likely in the small
yards of the working and middle classes, and would be less likely to limit the
choices of wealthier holders of large properties. Also, much of the decision making about “weediness”
of yards strikes me as arbitrary, based on plant height, the assumption that
mowing is the main management tactic, and the assumption that urban
disamenities such as rats are associated with these arbitrarily defined weeds. Oddly, many of these assumptions are not in
fact based on data. Rats, for example,
live in built structures or beneath hard surfaces that provide them
protection. They do not live in open
vegetation, whether “weedy” or otherwise.
Weeds and Continuing Urban Dyanamics
One lesson of the book is that weeds, or as I might
 |
Dr. Yvette Williams, studies a vacant lot in
Baltimore. Photo by Erica Tauzer. |
say as a
plant ecologist, plants adapted to open sites with uncontested resources, have
been a consistent part of our urban enterprise.
They occupy lands that are recently enfolded into municipal boundaries,
but which have yet to be built upon. At
the other extreme, they dominate in sites where the retreat of
industrialization and the reduction in residential density have left vacant
parcels. Well funded and extensive
efforts to eradicate weeds from our cities have conspicuously failed. The New York City program to abolish ragweed is a powerful example examined in detail by Falck. We will always have weeds in our city-suburban-exurban
systems.
Falck’s book examines many fascinating aspects of the
relationship of weeds with the dynamics of cities and the social and legal
processes that shape urban places. Legal
status of weeds illustrates concern with individual responsibility and the
perceptions of public good and of nuisance.
Mandates for management are based on perception, such as the association
with criminal activity. Often such
perceptions are driven by the occasional splashy correlation, rather than
careful consideration and evaluation of causality. This is perhaps not surprising given the deep
and powerful social view of weeds as sources of pestilence, as threats to
productivity, and as indicators of personal slovenliness.
A New View of Weeds for the 21st Century
As the 21st century dawns, Falck suggests that
rather than reevaluating the role of volunteer or pioneer plants in urban
systems, citizens and managers continue to fall back on tradition and long-held
biases. If anything, the fervor of
eradication long focused on weeds is now shifting to exotic, introduced
species. Unfortunately, the risk that
unexamined social biases merely transfers from weeds to exotics is great. Rather, threat, benefit, adaptation, and life
cycle, should be examined from both social and ecological perspectives. Otherwise, the excesses and failures of
eradication of plants well and long adapted to human-generated habitats and
stresses, will continue to sap resources and limit some of the benefits that these
resilient plants may well provide to our continually evolving cities, suburbs,
and exurbs.
For Further Reading
Falck, Z. J. S. 2010. Weeds: an environmental history of
metropolitan America. University of Pittsburgh Press, Pittsburgh.
Pickett,
S.T.A., and J.M. Baskin. 1973. The role of temperature and light in the
germination behavior of Ambrosia
artemisiifolia. Bulletin of the
Torrey Botanical Club 100:165-170. (now the Journal of the Torrey Botanical Society.)
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