Managing Spontaneous Urban Plants for Improved Aesthetics

As discussed last week, our wild, urban flora is a cosmopolitan mixture of plants that were either native to the area before it was developed, introduced from all corners of the world on purpose or by accident, or brought in by migrating wildlife. These are plants capable of establishing and sustaining themselves outside of human cultivation and management, and are found in abundance beyond the borders of our tidy gardens and manicured landscapes. They vegetate sectors of our city that have been abandoned, overlooked, or routinely neglected. Given enough time – and prolonged lack of intervention – such vegetation will proceed along the process of ecological succession in the same way that plant communities in natural areas do. And just like other plant communities within their respective ecosystems, these wild, urban plant communities provide a suite of ecological services vital to the health of our urban ecosystems.

Peter Del Tredici writes in Wild Urban Plants of the Northeast, “landscapes that include spontaneous vegetation fit the technical definition of sustainable in the sense that they are adapted to the site, require minimal maintenance, and are ecologically functional.” In an interview with Scenario Journal, Del Tredici goes on to define sustainability as “the value of the services provided by the ecosystem divided by the cost required to maintain that ecosystem.” Spontaneous urban landscapes offer “substantial ecological services at relatively low cost, or in some cases no cost,” and thus, by Del Tredici’s definition, they are “highly sustainable.”

There is one unfortunate downside – “weedy” landscapes like this are, by popular opinion, thoroughly unattractive and a sign of urban decay. This belief is held in spite of the fact that many of the plants found therein would be cherished or admired in other settings. Among deteriorating infrastructure, litter, and less attractive plants, some of our favorite plants are rendered guilty by association.

Despite their ecological benefits, abandoned areas vegetated with wild, urban plants are not favored by the public. So, to appease our aesthetic standards, sites like this can be enhanced through minimal intervention to be more attractive while retaining their ecological functions. In a paper published in a 2006 issue of Journal of Landscape Architecture, Norbert Kühn asserts that “to use spontaneous vegetation for ornamental purposes, a kind of enhancement or design work is necessary.” Species can be added and removed, and simple, infrequent maintenance measures can be implemented. Examples include extending the flowering season with spring flowering bulbs and mowing the area once or twice annually to maintain and improve the composition of the stand.

Wild bergamot (Monarda fistulosa) – one of the plants that Norbert Kühn included in his study as a candidate for improving the aesthetics of spontaneous, urban plant communities.

Favoring attractive weeds over less attractive ones and using minimal maintenance to improve aesthetics and function are the principles behind Del Tredici’s “cosmopolitan urban meadow.” In his book, he lists some criteria for plants that would be suitable for “this novel landscape form,” including: erosion control (long-lived; vegetatively spreading), stress tolerance (full sun; drought; compacted and polluted soil), aesthetic value (ornamental characteristics; not “weedy” looking), wildlife friendly (attractive to pollinators; edible seeds), and commercially available.

In an article in Harvard Design Magazine, Del Tredici and Michael Luegering describe the cosmopolitan urban meadow as “a stable assemblage of stress-tolerant, low-maintenance herbaceous perennial plants that are preadapted to harsh urban conditions and that will provide an attractive vegetation cover on vacant land.” Whether it is a “long-term landscape feature” or a placeholder until future development, it will have “the capacity to increase the aesthetic and ecological value of vacant land without the investment of large sums of money typically required for the installation and maintenance of traditional managed landscapes.”

Abandoned or undeveloped, urban lots like this one are ideal sites for “cosmopolitan urban meadows.”

In an urban context, some plant species are particularly noxious and may need to be removed from urban meadows, such as ragweed (Ambrosia spp.) for its allergens and poison ivy (Toxicodendron radicans) for its Urushiol-induced contact dermatitis. Species with a history of being invasive should also be avoided and contained, particularly in sites that are adjacent to or within a short distance from natural areas. Despite this and other minor concerns, spontaneous vegetation has great potential. In Kühn’s words it is “authentic” and a “reminder of the history of the site,” it is part of “the natural dynamic” with potential to bring us “closer to nature,” and finally, “it can be maintained for a long time [with] less care and low costs.”

Finding beauty in these urban, wild landscapes might even cause a shift in what we find appropriate for cultivated landscapes. In her book, Grow Curious, Gayla Trail reminds us that, despite all of our efforts, wildness persists even in our most earnest attempts to subdue it. Perhaps we should embrace it:

‘Wild’ and ‘cultivated’ are social constructs that we place in opposition to each other, when in reality there is a knotty labyrinth between them. We subjugate our cities and our gardens with chemicals and artifice because we are unable to see that wild and cultivated can be entwined, can be all at once tended, lyrical, surprising, domesticated, irrational, functional, and free.

———————

See Also: Arnold Arboretum’s Cosmopolitan Meadow at Weld Hill

Advertisements

Is There a Place for Weeds in Urban Ecosystems?

Highly urbanized areas have a long history of disturbance. They are a far cry from the natural areas they once displaced, bearing little resemblance to what was there before. In this sense, they are a brand new thing. During the urbanization process, virtually everything is altered – temperatures, soils, wind patterns, hydrology, carbon dioxide levels, humidity, light availability, nutrients. Add to that a changing climate and increased levels of pollution, and the hope of ever seeing such a site return to its original state – whatever that might mean – is crushed.

What then should we consider the natural flora of an ecosystem like this? Certainly it is not the native flora that once stood on the site before it was developed; virtually none of the conditions are the same anymore. If we are defining “natural” as existing with minimal human intervention, then the natural urban flora would be whatever grows wild outside of our manicured landscapes and managed, remnant natural areas. It would be a cosmopolitan mixture of plants that have joined us in our migrations with and without our permission, along with a collection of species that are either extant to the site or have been brought in by wildlife. In many ways it would mirror the human populations of our modern cities – an assortment of residents from around the globe with diverse backgrounds and cultural histories.

In Wild Urban Plants of the Northeast, Peter Del Tredici classifies urban land into three general categories based on their ecological functions: native, remnant landscapes; managed, constructed landscapes; and ruderal, adaptive landscapes. Native, remnant landscapes are generally small areas within city limits that have never been developed. They contain a portion of the native plants that once populated the area, and they require vigilant and regular maintenance to keep non-native plants from invading and to control those that already have. Managed, constructed landscapes include all of the parks and gardens that have been designed and intentionally planted. They require regular maintenance of varying intensity in order to keep them looking the way they are intended to look. Ruderal, adaptive landscapes are abandoned or neglected sites that are populated by plants that have arrived on their own and that maintain themselves with virtually no human intervention. This is where the true, wild urban flora resides.

Prickly lettuce (Lactuca serriola) growing in an abandoned lot.

Many of the plants that make up our wild urban flora are what we commonly refer to as weeds. These weedy plants appear in landscapes throughout our cities, but are generally removed or controlled in all landscapes except the abandoned ones. It is in these neglected sites that weeds have the greatest potential to provide vital ecosystem services, performing ecological functions that are beneficial to urban life.

Not all plants are suited for this role. Spontaneous urban vegetation is particularly suited due to its ability to thrive in highly modified, urban environments without external management. Regardless of provenance, this suite of plants, as Del Tredici points out, seem to be “preadapted” to urban conditions and “are among the toughest on the planet.” A long list of traits has been identified for plants in this category, ranging from seed dispersal and viability to speed of growth and reproduction to tolerance of harsh conditions. Del Tredici summarizes by stating, “a successful urban plant needs to be flexible in all aspects of its life history from seed germination through flowering and fruiting, opportunistic in its ability to take advantage of locally abundant resources that may be available for only a short time, and tolerant of the stressful growing conditions caused by an abundance of pavement and a paucity of soil.”

Abandoned lots flush with weeds, overgrown roadsides and railways, and neglected alleyways colonized by enterprising plants are generally seen as ugly, unsightly eyesores – products of neglect and decline. Some of the plants found in such locations are valued in a garden setting or prized as part of the native landscape in a natural area, but growing wildly among trash and decaying urban infrastructure they, too, are refuse. As Richard Mabey has written: “If plants sprout through garbage they become a kind of litter themselves. Vegetable trash.”

Abandoned chicken coop overtaken by tree of heaven saplings (Ailanthus altissima).

Despite how we feel about these plants or the aesthetics of the locations they find themselves in, they are performing valuable services. Apart from adding to the biodiversity on the site as well as producing oxygen and sequestering carbon – services that virtually all plants offer – they may be preventing soil erosion, stabilizing waterways, absorbing excess nutrients, reducing the urban heat island effect, mitigating pollution, building soil, and/or providing food and habitat for urban wildlife. While cultivated and managed landscapes can achieve similar things, these neglected sites are doing so without resource or labor inputs. They are sustainable in the sense that their ability to provide these services is ongoing without reliance on outside maintenance.

Sites like these should be further investigated to determine the full extent of the services that they may or may not be offering, and in the event that they are doing more good than harm, they should be conserved and encouraged. One service that is receiving more attention, as Del Tredici writes, is phytoremediation – “the ability of some plants to clean up contaminated sites by selectively absorbing and storing high concentrations of heavy metals such as cadmium, lead, copper, zinc, chromium, and nickel in their tissues.” Weed species with this ability include prickly lettuce (Lactuca serriola), lambsquarters (Chenopodium album), and mugwort (Artemisia vulgaris). In an article in Places Journal, Del Tredici gives the example of the often despised, introduced plant, common reed (Phragmites australis) cleaning up the New Jersey Meadowlands by “absorbing abundant excess nitrogen and phosphorous throughout this highly contaminated site.”

In the book, Weeds: In Defense of Nature’s Most Unloved Plants, Richard Mabey writes: “As we survey our long love-hate relationship with [weeds], it may be revealing to ponder where weeds belong in the ecological scheme of things. They seem, even from the most cursory of looks, to have evolved to grow in unsettled earth and damaged landscapes, and that may be a less malign role than we give them credit for.” Perhaps, seeing them in this worthy role, will temper our knee-jerk inclination to demonize them at every turn.

———————

See Also: Our Urban Planet and Wild Urban Plants of Boise.

Concluding the Summer of Weeds

“Most weeds suffer from a bad rap. Quite a few of the weeds in your garden are probably edible or even medicinal. Some invasive plants, including horsetail and nettle, are rich in minerals and can be harvested and used as fertilizer teas. Weeds with deep taproots, such as dandelions, cultivate the soil and pull minerals up to the surface. … Weeds are nature’s way to cover bare soil. After all, weeds prevent erosion by holding soil and minerals in place. Get to know the weeds in your area so you can put them to use for rather than against you.” — Gayla Trail, You Grow Girl

Great Piece of Turf by Albrecht Dürer (photo credit: wikimedia commons)

With summer drawing to a close, it is time to conclude the Summer of Weeds. That does not mean that my interest in weeds has waned, or that posts about weeds will cease. Quite the opposite, actually. I am just as fascinated, if not more so, with the topic of weeds as I was when this whole thing started. So, for better or worse, I will much have more to say on the subject.

In fact, I am writing a book. It is something I have been considering doing for a long time now. With so many of my thoughts focused on weeds lately, it is becoming easier to envision just what a book about weeds might look like. I want to tell the story of weeds from many different angles, highlighting both their positive and negative aspects. There is much we can learn from weeds, and not just how best to eliminate them. Regardless of how you feel about weeds, I hope that by learning their story we can all become better connected with the natural world, and perhaps more appreciative of things we casually dismiss as useless, less quick to jump to conclusions or render harsh judgments about things we don’t fully understand, and more inclined to investigate more deeply the stories about nature near and far.

Of course, I can’t do this all by myself. I will need your help. If you or someone you know works for or against weeds in any capacity, please put us in touch. I am interested in talking to weed scientists, invasive species biologists, agriculturists and horticulturists, edible weed enthusiasts, plant taxonomists, natural historians, urban ecologists, gardeners of all skill levels, and anyone else who has a strong opinion about or history of working with weeds. Please get in touch with me in one of several ways: contact page, Facebook, Twitter, Tumblr, or by commenting below.

Another way you can help is by answering the following poll. If there is more than one topic you feel particularly passionate about, feel free to answer the poll as many times as you would like; just wait 24 hours between each response. Thank you for your help! And I hope you have enjoyed the Summer of Weeds.

Quick Guide to the Summer of Weeds:

Summer of Weeds: Wild Urban Plants of Boise

The Summer of Weeds is a result of the curiosity and fascination I feel towards weeds. It is also inspired by Peter Del Tredici’s book, Wild Urban Plants of the Northeast, which encouraged me to take a closer look at the weeds that grow in my urban hometown of Boise, Idaho. Del Tredici’s book serves mainly as a field guide for identifying common weeds found in urban areas in the northeast region of the United States. Many of these weeds are found in cities across North America, so the guide is still useful regardless of where you live. Additionally, the book’s 25 page introduction is an excellent overview of how weeds fit in to the ecology of urban areas and an incentive to not only stop and get to know our urban flora but to respect it for its tenacity and durability and its important ecological role.

Excerpts from Wild Urban Plants of the Northeast by Peter Del Tredici:

From the Foreword by Steward T. A. Pickett –

If it is to fulfill its potential, the urban wild flora must be better understood and better used. In other words, its functions, not just its categories – native, exotic, invasive, naturalized – must be appreciated by professionals and citizens alike. Understanding should come before judgement when urban wild plants are concerned.

Defining urban wild plants –

The [plants] that fill the vacant spaces between our roads, our homes, and our businesses; take over neglected landscapes; and line the shores of streams, rivers, lakes, and oceans. Some of the plants are native to the region and were present before humans drastically altered the land; some were brought intentionally or unintentionally by people; and some arrived on their own, dispersed by wind, water, or wild animals. They grow and reproduce in the city without being planted or cared for. They are everywhere and yet they are invisible to most people. Given that cities are human creations and that the original vegetation that once grew there has long since disappeared, one could argue that spontaneous plants have become the de facto native vegetation of the city.

Why weeds are problematic in agricultural and horticultural settings, as well as in natural areas, is fairly intuitive. But why are they seen as a problem in urban areas, outside of our parks, yards, and gardens? –

When it comes to spontaneous urban plants, people’s complaints are usually aesthetic (the plants are perceived as ugly signs of blight and neglect) or security related (they shield illicit human activity or provide habitat for vermin). Indeed, the context in which a plant is growing not only determines the label that we put on it but also the positive or negative value that we assign to it.

Regarding urban ecology – 

[Cities] have their own distinctive ecology, dominated by the needs of people and driven by socioeconomic rather than biological factors. People welcome other organisms into cities to the extent that they contribute to making the environment a more attractive, more livable, or more profitable place to be; and they vilify as weeds those organisms that flourish without their approval or assistance. Regardless of humans’ preferences, an enormous variety of nonhuman life has managed to crowd into cities to form a cosmopolitan collection of organisms that is every bit as diverse as the human population itself.

To illustrate the point that urban weeds are playing a role in the ecology of our cities, Del Tredici lists the ecological functions of each species featured in the field guide portion of the book. These functions include:

  • temperature reduction
  • food and/or habitat for wildlife
  • erosion control on slopes and disturbed ground
  • stream and river bank stabilization
  • nutrient absorption (nitrogen, phosphorous, etc.) in wetlands
  • soil building on degraded land
  • tolerance of pollution or contaminated soil
  • disturbance-adapted colonizer of bare ground

Carbon storage and oxygen production are functions of these plants as well, as they are of all plants; however, as Del Tredici points out, “because [spontaneous urban plants] grow on marginal sites and require no maintenance, [they] are probably providing a greater return in terms of carbon sequestration than many intentionally cultivated species.”

There is much more to say about this “brave new ecology” and the role that urban wild plants play in it. Future posts are in the works. For now, consider this sentiment from Del Tredici’s book: Urban wild plants “are well adapted to the world we have created and, as such, are neither good nor bad – they are us.”

What follows are a few photos of some of the urban wild plants I have encountered in Boise over the last few weeks. These, along with the plants featured in previous Summer of Weeds posts, are a mere fraction of the species that grow wild in my urban hometown. The diversity of weeds alone in urban areas is astounding and should be given more consideration, along with the broader diversity of organisms that exist within our cities.

Creeping wood sorrel (Oxalis corniculata) along the driveway in front of my apartment

Prickly lettuce (Lactuca serriola) in an abandoned lot on Bannock Street

Yet to be identified thistle along 23rd Street

Field horsetail (Equisetum arvense) in front of post office on 13th Street

Pale smartweed (Polygonum lapathifolium) in a ditch at Idaho Botanical Garden

Tree of heaven seedling (Ailanthus altissima) in the backyard of my apartment

Birdsfoot trefoil (Lotus corniculatus) in the lawn at Esther Simplot Park

Weeds taking over a recently abandoned business on 27th Street

Creeping bellflower (Campanula rapunculoides) in the alleyway behind my apartment

Showy milkweed seedlings (Asclepias speciosa) next to horizontal juniper in a median on Parkcenter Boulevard

Purple loosestrife (Lythrum salicaria) on the bank of the Boise River near the Broadway Avenue bridge

Himalayan blackberry (Rubus armeniacus) along the Boise River Greenbelt near MK Nature Center

Summer of Weeds: Eating Purslane

If it wasn’t so prolific and persistent, purslane would probably be a welcome guest in our vegetable gardens and edible landscapes. Easily among the most nutritious and versatile of the edible weeds, Portulaca oleracea is an annoyingly abundant annual that has inserted itself into garden beds and croplands in temperate climates across the globe. Thought to have originated in India or somewhere in Eurasia, purslane invaded North America long before Europeans did and has been naturalized across much of the continent for hundreds of years.

common purslane (Portulaca oleracea)

There are over 100 known species in the genus Portulaca, the only genus in the family Portulacaceae (otherwise known as the purslane family). Common purslane is a succulent plant with paddle- or teardrop-shaped leaves that generally grows low to the ground, forming a thick mat. It reaches for the sky when grown in shade or when competing with other plants for space. It produces little, yellow flowers that only open in bright sun and are typically self-pollinated. A small capsule containing dozens of tiny, black seeds quickly follows each flower. Each plant can produce tens of thousands of seeds, which remain viable for around 40 years.

Attempts to remove purslane by cultivation may only aid its survival. Broken pieces of the plant can take root in the soil, and uprooted plants can re-root if they are in contact with soil. Stirring up the ground brings to the surface seeds from purslane’s extensive seed bank. These freshly exposed seeds can then germinate, taking advantage of disturbance and open space. For all these reasons and more, John Eastman writes in The Book of Field and Roadside: “Purslane knows how to live and linger.”

The ever-urban and ever-common purslane.

The seeds of purslane germinate in late spring and throughout the summer when the soil has reached at least 75 – 80° Fahrenheit. It is adapted to high heat and dry soils. In order to conserve water, it switches to CAM photosynthesis when conditions are particularly hot and dry. In this photosynthetic pathway, carbon dioxide is stored as malic acid during the night and then converted back during the day. This means that, when it comes to eating purslane, the flavor changes depending on when the plant is harvested. In The Wild Wisdom of Weeds, Katrina Blair discusses this phenomenon: “In the morning purslane leaves contain as much as ten times more malic acid, making them very sour tasting. If you prefer a milder tasting purslane, harvest your greens in late afternoon and if you want more zing to your recipes, gather the leaves at dawn.”

Speaking of eating purslane, if all the claims are to be trusted, there may not be a more nutritious weed. In A Feast of Weeds, Luigi Ballerina calls it “a health bomb” because “it contains more omega-3 fatty acids than almost any other green, not to mention vitamins A, B, and C and beta carotene.” Blair calls it “one of the most nutritious plants on Earth,” and goes on to sing praises about its richness in dietary fiber, vitamins, minerals, protein, etc. Funnily enough, in describing the health benefits of purslane, Ballerina also quotes ancient sources claiming that “purslane calms sexual excitement.” Apparently it not only “eliminate[s] sensual dreams, but if used too much, it often extinguishes all ardor and even the capacity to procreate.”

With that caveat in mind, I tried it anyway. I had eaten it before, but nothing more than a leaf here and there and once in a green salad. I picked two recipes to try: Walnut Purslane Coleslaw from The Wild Wisdom of Weeds and Potatoes and Purslane from A Feast of Weeds. I’m generally a big fan of coleslaw, but for whatever reason I found this recipe to be a little bland. It was missing something, but I couldn’t put my finger on it. The purslane seemed to add a vague slimy-ness to it, which it will do on account of its mucilaginous nature.

Walnut Purslane Coleslaw

The Potatoes and Purslane recipe involved cooking the purslane. I enjoyed the finished product both hot and cold. The purslane added a sort of lemon-y spinach flavor. Those who tried it with me also liked it. The potato recipe was made with purslane that had been harvested in the morning, which may explain the strong lemon-y flavor. The coleslaw was made with purslane harvested in late afternoon, which may explain its blandness. I will have to try it the other way around for comparison. Purslane recipes abound in books and on the internet; browsing through them, I am intrigued enough to consider trying others. I think I’ll start with pickled purslane, purslane pesto, and perhaps, purslane sauerkraut.

Potatoes and Purslane

More Resources:

———————

Do you have a favorite purslane recipe? Share it in the comment section below.

Book Review: Weeds Find a Way

At what age do we become aware that there are profound differences among the plants we see around us? That some are considered good and others evil. Or that one plant belongs here and another doesn’t. Most young children (unless an adult has taught them) are unaware that there is a difference between a weed and a desirable plant. If it has attractive features or something fun to interact with – like the seed heads of dandelions or the sticky leaves of bedstraw – they are all the same. At some point in our trajectory we learn that some plants must be rooted out, while others can stay. Some plants are uninvited guests – despite how pretty they might be – while others are welcome and encouraged.

But weeds are resilient, and so they remain. Weeds Find a Way, written by Cindy Jenson-Elliot and illustrated by Carolyn Fisher, is a celebration of weeds for their resiliency as well as for their beauty and usefulness. This book introduces the idea of weeds to children, focusing mainly on their tenacity, resourcefulness, and positive attributes rather than their darker side. “Weeds are here to stay,” so perhaps there is a place for them.

The book begins by listing some of the “wondrous ways” that weed seeds disperse themselves: “floating away on the wind,” attaching themselves to “socks and fur,” shot “like confetti from a popped balloon.” And then they wait – under snow and ice or on top of hot sidewalks – until they find themselves in a time and place where they can sprout. Eventually, “weeds find a way to grow.”

Weeds also “find a way to stay.” We can pull them up, but their roots are often left behind to “sprout again.” Pieces and parts break off and take root in the soil. Animals may swoop in to devour them, but weeds drive them away with their thorns, prickles, and toxic chemicals. In these ways they are a nuisance, but they can be beautiful and beneficial, too.

This illustrated story of weeds is followed by some additional information, as well as a list of common weeds with brief descriptions. Weeds are defined as plants “thought to be of no value that grow in places where people do not want them to grow,” adding that even “misunderstood and underappreciated plants that are native to a region and have multiple uses” can be labeled weeds.

The concept of weeds as invasive species is also addressed; some introduced plants move into natural areas and can “crowd out native vegetation, block streams, and drive away wild animals.” That being said, weeds also provide us with “endless opportunities to study one of nature’s most wonderful tools: adaptation.” Weeds are problematic as much as they are useful, it’s simply a matter of perspective.

A criticism of this book might be that it doesn’t focus enough on the negative aspects of weeds. There is plenty of that elsewhere. The aim of this book is to connect us with nature, and as Jensen-Elliot writes, “you don’t need a garden to know that nature is at work.” When there is a weed nearby, nature is nearby. Weeds “adapt and grow in tough times and desolate places,” and they make the world beautiful “one blossom at a time.”

Summer of Weeds: Pineapple Weed

“The spread of the fruitily perfumed pineapple weed, which arrived in Britain from Oregon in 1871, exactly tracked the adoption of the treaded motor tyre, to which its ribbed seeds clung as if they were the soles of small climbing boots.” – Richard Mabey, Weeds: In Defense of Nature’s Most Unloved Plants

Can a plant that is native to North America be considered a weed in North America? Sure. If it is acting “weedy” according to whatever definition we decide to assign to the word, then why not? Can “weeds” from North America invade Europe the same way that so many “weeds” from there have invaded here? Of course! Pineapple weed is just one such example.

Native to western North America and northeastern Asia, this diminutive but tough annual plant in the aster family can now be found around the globe. Matricaria discoidea gets its common name from the distinctive fruity scent it gives off when its leaves and flowers are crushed. Its scent is not deceptive, as it is yet another edible weed (see Eat the Weeds). Teas made from its leaves have historically been used to treat upset stomachs, colds, fevers, and other ailments.

pineapple weed (Matricaria discoidea)

Pineapple weed reaches as few as a couple centimeters to a little over a foot tall. Its leaves are finely divided and fern-like in appearance. Its flower heads are cone or egg-shaped, yellow-green, and cupped in light-colored, papery bracts. The flower heads lack ray florets and are composed purely of tightly packed disc florets. The fruits (i.e. seeds) are tiny, ribbed achenes that lack a pappus.

Compacted soils are no match for pineapple weed. It is often seen growing in hard-packed roadways and through small cracks in pavement, and it is undeterred by regular trampling. It is a master of disturbed sites and is commonly found in home gardens and agriculture fields. It flowers throughout the summer and is often confused with mayweed (Anthemis cotula); the telltale difference is that mayweed gives off a foul odor when crushed.

Meriwether Lewis collected pineapple weed along the Clearwater River during the Lewis and Clark Expedition. In their book, Lewis and Clark’s Green World, Scott Earle and James Reveal write, “There is nothing in the expedition’s journals about the plant, but it would seem that there was little reason for Lewis to collect the two specimens that he brought back other than for its ‘agreeable sweet scent.’ It is otherwise an unremarkable, rayless member of the aster family.” The authors continue their mild ribbing with this statement: “The pineapple weed deserves its appellation, for it is a common weed – although a relatively innocuous one – that grows in disturbed places, along roadsides, and as an unwanted garden guest.”

pineapple weed (Matricaria discoidea) – photo credit: wikimedia commons

More Resources:

Quote of the Week:

From Weeds and What They Tell (ed. 1970) by Ehrenfried Pfeiffer

“Weeds are WEEDS only from our human egotistical point of view, because they grow where we do not want them. In Nature, however, they play an important and interesting role. They resist conditions which cultivated plants cannot resist, such as drought, acidity of soil, lack of humus, mineral deficiencies, as well as a one-sidedness of minerals, etc. They are witness of [humanity’s] failure to master the soil, and they grow abundantly wherever [humans] have ‘missed the train’ – they only indicate our errors and Nature’s corrections. Weeds want to tell a story – they are natures way of teaching [us] – and their story is interesting. If we would only listen to it we could apprehend a great deal of the finer forces through which Nature helps and heals and balances and, sometimes, also has fun with us.”