Natural Notes: A History of some of our most common urban "weeds"

Did you know that Illinois has a state "nickname?"  In fact, most state's do, and the nickname for Illinois is the "Prairie State."  A prairie is an open grassland without much trees that thrives in semi-arid climates, or in the case of Illinois, in areas frequented by wildfires (figure 1).  Wildfires prevent encouragement of woody trees and shrubs to allow sun-loving and deep-rooted prairie grasses and flowers to thrive.  Illinois at one point was covered with about 60% tall-grass prairie, but today less than 1% remains.  The city of Chicago was once a mixture of wetlands and prairies with small patches of forest.

Figure 1:  Tallgrass prairie in the northwest suburbs of Chicago.  

Over time, however, and with European colonization and eventual industrial development, the landscape and the flora and fauna found upon it changed dramatically.  Removal of topsoil, chemical pollution, introduction of non-native and invasive plants and other anthropomorphic changes, altered the composition of the wild-growing plants and animals found in Chicago. Today, we see plants that were once rare or absent from North America now commonplace along roadsides, abandoned lots, lawns and...the Taylor Street Farms community garden in Chicago.  Here are just few of these plants and the stories they tell about our immigrant landscape:

Dandelion (Taraxacum officinale)

Figure 2:
 Illustration of a Dandelion. 
Image source

Native to Europe and Asia, this common lawn weed was beloved by European Colonists for its various medical and culinary uses, such as relieving digestion issues, a vitamin supplement, a garnish on salads and even wine and tea.  The word "dandelion" is derived from the French and translates as "lion's claw", as the jagged lobes of its leaves resemble sharp hooks or claws.  Most Americans loath Dandelions, and many municipalities spend hundreds of thousands of dollars each year on herbicides intended to kill this hardy and resilient wildflower.  Although non-native, dandelions are an important pollinator flower that attracts numerous beneficial insects.

Figure 3:  Kentucky Bluegrass
growing wild

Kentucky Blue Grass (Poa pratensis)
The most common turf grass used in the modern American Lawn, this cultivated grass that originated in Europe offers the Taylor Street Farms a park-like ambiance.  When Kentucky Blue Grass was introduced to the United States (Kentucky being the first of many locations), it was planted for a much different purpose.  Imported livestock such as cows and sheep preferred their homeland food source, and so this grass was planted across pastures as a grazing crop.  As our country urbanized, this grass became a popular choice as a ground cover for parks and lawns, bringing in that "country" feel to the cityscape. 




Canada Thistle (Cirsium arvense)

Figure 4: 
Canada Thistle.  Photo credits:  MrJones

This aggressive invasive plant spreads by rhizomes, or an underground network of roots that produce vertical shoots.  Native to Europe, it was accidentally brought to North America in a delivery of livestock feed to Canada.  This wildflower is tolerant of harsh conditions  - sometimes places with little or no topsoil, and spreads rapidly.  Birds such as finches eat the seeds, which helps this plant to proliferate even more.  Any outbreaks of Canada Thistle must be dealt with quickly and early to prevent the formation of a monoculture.  In fact, Canada Thistle was one of the first non-native invasive plants to be regulated by the government, officially banned in Illinois during the passage of an 1872 weed law.

Figure 5:  Illustration of Mugwort
Image credits:
Franz Eugen Köhler, Köhler's Medizinal-Pflanzen

Mugwort (Artemesia vulgaris)
Mugwort is native to Europe and was likely brought to North America on purpose, as it has various medicinal and culinary uses.  This plant is extremely hardy and can be seen growing along the 'L' tracks in Chicago and in other waste places around the city.  This wildflower can reproduce rapidly and produce many seeds, and will quickly invade an unkempt garden plot.  Ironically, this same plant is prized amongst Asians, and you'll find a wide variety of Mugwort food and herbal products in Asian supermarkets such as the H-Mart in the West Loop neighborhood of Chicago.



Broadleaf Plaintain (Plantago major)

Figure 6:  Broad-leaved Plantain

A ubiquitous lawn weed, this wildflower tolerates highly compacted soils, including lawns with frequent foot traffic.  This was believed to be one of the first European plants to be brought over to North America by settlers, and in fact Native Americans once nicknamed this leafy herb "white-man's footprint since it seemed to grow in areas where white settlers had passed.  The flower heads are long and stiff, and produce hundreds of seeds which stick to clothing, hair and shoes, allowing this wildflower to quickly expand its range.  In fact, the diminutive nickname of "white man's foot" was not entirely out of place, as Europeans would use the leaves as a foot salve inside their shoes and were likely responsible for its distribution. 

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Our urban landscape is now dominated by these non-native plants because of the hands of people changing the landscape.  These plants are immigrants, some brought on purpose and others by accident.  The ones that were brought here intentionally had a distinct purpose, such as to feed livestock, for use in medicine and foods, or sometimes to give the "new world" a more familiar feel. Now that we have made so many changes to the very foundation of our local environment, these plants pop-up everywhere, including in undesired places such as our vegetable garden or ornamental flower bed.   So the next time you are doing your garden weeding, perhaps you'll pause a moment to think of the stories of our past that are revealed through the lenses of our most common urban weeds, revealing the consequences of the choices our society has made. 

Much of the research for this blog post relied on the previous research of Dr. Ann Durkin Keating, the Toenniges Professor of History at North Central College; Gavin Van Horn, director of cultures of conservation for the Center for Humans and Nature; and Sam Cholke of Illinois Humanities.