weeds – Conservation Sense and Nonsense

Weeds are making a comeback!

While the native plant movement remains strong in California and locally in the San Francisco Bay Area, some communities are waking up to the fact that weeds make valuable contributions to our gardens and the wildlife that lives in them. The British have always been ahead of us in welcoming plants from all over the world in their gardens. The British have bee n enthusiastic importers of plants from all over the world for hundreds of years. They had one of the biggest empires in the world, spanning the globe from India to Africa, Australia, New Zealand, and America, which put them in a unique position to sample the botanical riches of the world.

The English garden, where plants from all over the world are welcome

In a recent article in The Guardian, an English gardener describes her journey from fighting the weeds in her garden to her new relationship with them: “I remember writing, many years ago, about my fight to get rid of these dandelions. Clearly, I didn’t win. Now, when I am greeted by them, I am glad I lost the battle. These days, I truly consider them friends…they are welcome in my garden, because I know they do more good than harm.”

The English gardener reminds us that the war on weeds began only recently. Going deep into agricultural history, weeds were natural forage that were a part of our diet. Weeds fed our domesticated animals, stuffed our mattresses and made twine and rope. Many have medicinal properties, but most have marketable substitutes now. They were tolerated on the edges of agricultural fields and in our gardens.

The typical American lawn, maintained with pesticides and fertilizer is not habitat for pollinators or other insects. Source: Pristine Lawn Care Plus

The war on weeds began after World War II, when chemicals were introduced to agriculture. Pesticides were considered benign for decades. We have learned only recently of the dangers of some pesticides. The promotion of pesticides changed the aesthetics of gardening, initiating an era in which weeds were banished from our agricultural fields and our gardens.

Note the drone hovering over the children in a strawberry field. Drones are the latest development in chemical warfare. They are used to spot non-native plants in open space as well as to aerial spray pesticides. They are cheaper than other methods of application and for that reason are likely to increase the use of pesticides.

Do not underestimate the power of propagand a to promote the use of pesticides: “A publishing company linked to the most powerful agricultural lobby group in the U.S. is releasing children’s books extolling the benefits of pesticides and nitrogen fertilizers.” Industrial agriculture begins the indoctrination of the public at childhood.

Bumblebee in clover. Source: buzzaboutbees.net

Weeds made their way back into our gardens partly by evolving resistance to the pesticides we used for decades to kill them. There is growing awareness of the impact of pesticides on insects and wildlife. As populations of pollinators decline, we are more willing to indulge their preference for weeds such as dandelions and clover. Weeds are often the first to arrive in the spring garden, as native bees are emerging from their winter hibernation in ground nests. Weeds prolong the blooming season in our gardens, providing nectar and pollen before cultivated plants are blooming.

“No Mow May” comes to America!

“No Mow May” originated in Britain out of concern for declining populations of bees. Communities make a commitment to stop mowing their lawns in May to let the weeds dominate their lawns. Weeds such as dandelions and clover give the bees an early boost in the spring that studies show increases bee populations. Lawns maintained with pesticides and fertilizers provide poor habitat for bees.

Two professors in the Midwest of the US introduced “No Mow May” to their community in Wisconsin in 2020. They signed up 435 residences to participate in “No Mow May” and studied the impact: “They found that No Mow May lawns had five times the number of bees and three times the bee species than did mown parks. Armed with this information, they asked other communities to participate.” According to the New York Times, “By 2021, a dozen communities across Wisconsin had adopted No Mow May. It also spread to communities in Iowa, Minnesota, Illinois and Montana.”

Farmers climb on board

Hedgerows are the backbone of the English countryside. They are a complex bramble of woody and herbaceous plants that traditionally served as fences, separating roads from agricultural fields and confining domesticated animals. They nearly disappeared when industrial agriculture dictated that fields be cultivated from edge to edge. They are making a comeback in the English countryside as farmers realize that their loss contributed to the loss of wildlife. The concept of hedgerows as vital habitat is slowly making its way to America.

US Department of Agriculture reports improvements in agricultural practices in the past 10 years: more no-till farming that reduces fossil fuel use and carbon loss from the soil; more efficient irrigation methods; broader field borders for pollinators and wildlife; more crop rotations that reduce disease and insect pests; reduction of nitrogen and phosphorous run-off; reduction in diesel fuel use, etc. These are all well-known methods of reducing environmental damage from industrial agriculture, but there is now evidence that farmers are actually adopting them.

Nativists are late to the game

We see progress being made to reduce pesticide use and provide more diverse habitat for wildlife, but nativists drag their feet. They continue to use pesticide to eradicate non-native plants and they deny the value of non-native plants to insects and wildlife, despite overwhelming evidence to the contrary.

In a recent commen t posted on Conservation Sense and Nonsense, a nativist explains the justification for using herbicides to eradicate non-native plants: “No one likes herbicides, but in the absence of a labor force willing to abandon its modern conveniences to do very hard work, they are important tools in restoration ecology, and methods are improving as a result of careful science to determine how the least amount of them could be used to gain the greatest amount of benefits to the maximum amount of species. Throwing those tools away is about like tossing chemotherapy or vaccinations because of that “all-or-nothing” black or white point of view that native plant supporters are being (unjustly) accused of.”

For nativists, the harm done by non-native plants is greater than the harm done by pesticides. This equation does not take into consideration the benefits of many non-native plants to wildlife and it underestimates the damage caused by pesticides to the environment and its inhabitants.

Weed Worshipers vs. Weed Warriors

Native plant advocates who volunteer to pull weeds often call themselves “Weed Warriors.” Now there is a countervailing movement of weed advocates who find value in the same plants that are detested by the native plant movement. Weed worshippers are found in the permaculture community because they share a desire to avoid the use of herbicides. We also find them amongst foragers who think of weeds as a source of nutritious, free food. These origins of weed worship come together into a coherent botanical philosophy in a recently published book, The Wild Wisdom of Weeds: 13 Essential Plants for Human Survival, by Katrina Blair. (1)

Ms. Blair grew up in Colorado, in a family that lived close to nature. She developed her interest in wild plants early and has spent her life cultivating that interest both with her formal education and her experiences. She is the founder of Turtle Lake Refuge in Durango, Colorado. This is the mission of Turtle Lake Refuge:

“Our mission is to celebrate the connection between personal health and wild lands. We manifest this goal through promoting and practicing sustainable practices. Examples of our work include growing, harvesting and preparing local, wild and living food for the community, educating about the great values of the wild edible abundance available in our area, providing local micro-greens for the public schools, restaurants and stores…and educating about organic land stewardship practices.”

Turtle Lake Refuge serves lunch in their community twice each week. Here is a sample menu from a spring lunch, which reflects their commitment to “wild edible abundance:”

– Comfrey and hollyhock Green Juice:

Comfrey, hollyhock, lemon and honey

– Miso Soup:

Miso, tamari, fresh chives, cabbage and red onion

– Quinoa Beet Salad:

Sprouted Quinoa, beets, tamari, sunflower oil, ginger and garlic

– Sushi Roll:

Seed cheese, beets, buckwheat sprouts, pea sprouts and avocado

– Poppy seed Lemon Bar:

Buckwheat flour, honey, lemons, cashews psyllium and poppy seeds

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Why weeds?

Ms. Blair explains why she has selected 13 weeds for her book which are found all over the globe, wherever human civilization is found, that is every continent except Antarctica. They are therefore representative of the plants that often arrive with humans and are capable of surviving whatever changes in the environment accompany human civilization. In a sense, they are symbols of resilience and adaptation in a rapidly changing world. She also tells us why weeds are just as important as the native plants that preceded the arrival of humans:

“Humans are creating change on a large scale at an exceedingly rapid rate, and yet if we try to hold back nature by eradicating every new species that appears on a barren land, we block nature’s progression of adaptation. There is an accepted perspective that change is negative and therefore justifies momentous efforts to block diversity from becoming established for fear that it will alter the native habitat. It is important to remember that “native” habitat only represents a moment in time. All habitats evolve and are changing constantly. If the wild weeds are resilient enough to be able to handle the climate and take root, they play an important role in the evolutionary aspect of nature.” (1)

Dandelions

The thirteen weeds that Ms. Blair chooses to tell us about in her book are: amaranth, chickweed, clover, dandelion, dock, grass, knotweed, lambsquarter, mallow, mustard, plantain, purslane, and thistle. We have chosen the dandelion to illustrate the usefulness of weeds because it is plentiful and well known in the San Francisco Bay Area.

Dandelions are found everywhere. The origins of its English name are found in its name in romance languages: diente de leon (Spanish), dent-de-lion (French), diente di leone (Italian). These names all translate to “teeth of the lion” in English, a name that surely derives from the deeply jagged leaf, which apparently suggested the shape of the teeth of the lion. When named by the English, that reference to the shape of the leaf was lost in translation.

Dandelion seeds may have been brought by humans to new homes because they were known to be useful. But dandelions are not dependent upon intentional transport. Their wooly seed heads are dispersed by the wind and readily attach themselves to grazing animals. I remember blowing them into the wind as a child, oblivious to the fact that I was dispersing their seeds in the process.

An early reference to dandelions is found in the writing of the Roman military commander and naturalist, Pliny the Elder in 77 AD. He explained the healing properties of dandelions. Dandelions are used in Chinese herbal medicine—possibly for thousands of years—as well as in Indian traditional medicine, ayurvedic medicine. Ms. Blair uses dandelions to treat a wide variety of medical conditions, from a laxative to an anti-inflammatory which reduces swelling.

Every part of the dandelion, from its roots to its leaves is edible, according to Ms. Blair. The roots are used to make dandelion beer for the annual Dandelion Festival at Turtle Lake Refuge. Dandelion ice cream is also popular at the festival. Ms. Blair provides recipes for Dandelion Pesto, Dandelion Quiche, Dandy Candy, and Dandelion Root Stew. We are most familiar with dandelions as a salad green which adds bite to any salad.

Dandelion is equally useful to bees and butterflies because it is one of the first flowers in the spring.

The Druid’s Garden recently published a post about the usefulness of dandelions, including a description of how they can restore degraded soil.

Ms. Blair makes a similar case for the usefulness of the other 12 members of her weed family.

Opposition to herbicides follows….

As you might expect, if you eat wild plants you are probably opposed to use of herbicides in the places where you forage for your food:

“My deep passion for honoring the wild weeds intensified due to our local city and county’s practices in weed control. Hundreds of gallons of herbicides were being sprayed on the plants in town and on nearby wildlands with the intention of eradicating plant species considered weeds. Since I grew up loving all plants equally, I found it tragic to witness a once healthy plant that was contributing so much richness to our landscape become a twisted and dying being due to poisoning from herbicides. My passion for all plants inspired me to do what I could to change the discriminatory treatment of these noble weeds, who I have come to know as the true heroes of our time.” (1)

Ms. Blair tells the story of how she and her collaborators were successful in convincing the City of Durango to quit using herbicides in public parks. It is both an interesting story and one from which we can learn. They began by showing people how to use the weeds they were killing. The “Dandelion Brigade” harvested dandelions from their neighbors’ lawns and showed them how to make dandelion lemonade and other taste treats. They started an organic lawn service called “Grassroots” which made and distributed organic compost. These efforts convinced the city to create its first chemical-free public park, and eventually a second park. Then their efforts stalled because the city decided these two parks gave the public sufficient chemical-free options.

The second stage of their effort began with a ballot measure that, if passed, would have banned all herbicide use from every public park in Durango, including golf courses. They spent many months lobbying in support of that new ordinance and were confident that it would pass. Apparently the city was afraid it would pass as well and therefore began to negotiate with the supporters of the ordinance. This negotiation resulted in a compromise which accomplished much of what supporters of the ordinance set out to do. Although they still believed in the ordinance as originally written, they decided that a compromise would ultimately result in greater support throughout the community. The first phase of the compromise plan converted over one-third of the parks to organic management. The second phase would slowly transition most parks—except golf courses—to organic management methods.

The process of changing city policies regarding herbicide use was long and difficult. It required both patience and a willingness to meet people halfway by showing them how to substitute for herbicide use and by being willing to compromise.

Local foragers

Ms. Blair is not alone. She is a member of a big and growing movement. The favorable review of Ms. Blair’s book in the New York Times is an indication that foraging and respect for weeds are now in mainstream culture. Closer to home, we have our own contingent of lovers of wild food, which often includes plants commonly considered weeds:

“The Wild Kitchen is a roving underground supper club. From a roof-deck in the Mission one week to a houseboat in Sausalito the next, The Wild Kitchen knows no geographic bounds. One hundred diners sit around the communal table, enjoying eight course meals, each course highlighting a sustainably foraged ingredient from the local landscape. These meals connect the eater with their natural surroundings in a new way. The Wild Kitchen brings eaters together to grow community around the foods nature provides.”
“Reaping without Sowing: Urban Foraging and Berkeley Open Source Food” is a research project at UC Berkeley which is “studying the availability, nutritional value, and possible toxicity of wild edibles that volunteer in urban food deserts. Our research hypothesis is that in many such areas, there is a free, abundant source of nutritious fresh food: edible weeds.” The project identifies both native and non-native edible plants growing wild in the San Francisco Bay Area.
Quinoa plant – photo by Christian Guthier from Flickr

Quinoa is a specialty food item, found in high-end stores such as Whole Foods. It is growing wild along roadsides in Los Angeles because it is a plant that thrives on disturbance. Quinoa is an example of a plant that is adapted to human civilization and is also a source of food.

We hope that the foraging movement will grow and eventually become as strong and influential as the native plant movement has been in the past. And we hope that herbicide use in our public lands will be abandoned in the process of making the transition from venerating native plants to respecting ALL plants.

Katrina Blair, The Wild Wisdom of Weeds: 13 Essential Plants for Human Survival, Chelsea Green, 2014

Wily weeds win the war

Farmers have been battling with weeds since the advent of agriculture, about 6,000 years ago. Most of the weapons used against weeds were mechanical until the last century or so when herbicides became the primary weapon. At the same time that the weapon became more lethal, farming techniques changed to give weeds the advantage. Farms became huge monocultures and crop rotations were abandoned in favor of the most profitable crop.

When weeds evolved defenses against the herbicides, farmers responded by increasing doses and manufacturers created new products to which weeds hadn’t yet evolved resistance. Finally, the use of herbicides skyrocketed when crop seeds were invented that weren’t killed by the herbicides, so that huge amounts of herbicides can be used without killing the crop.

When Roundup with the active ingredient glyphosate went on the market in the 1970s, its manufacturer, Monsanto, claimed that weeds would not be able to evolve resistance to it. And apparently that was initially true until Roundup was used on a huge scale when herbicide-resistant seeds were put on the market in the 1980s. Norman Ellstrand of UC Riverside explains why: “He argues that the reason was that farmers applied glyphosate to relatively little farmland. As they applied it to more and more acreage, they raised the evolutionary reward for mutations that allowed weeds to resist glyphosate. ‘That ups the selection pressure tremendously,’ he said.” *

There are now 24 species of weeds that are resistant to glyphosate and they are rapidly expanding their range in agricultural areas all over the world. In 2012, an agricultural consulting firm reported that 34% of farms in the US had glyphosate-resistant weeds. In the first half of 2013, half of all farms in the US are reporting glyphosate-resistant weeds.

Let’s take another approach

Obviously, we are losing the war against weeds. So, let’s examine the strategy we have been using and try another approach. Weed ecologists are now studying the strategies that weeds have used to cope with the weapons we have been using against them. Here are a few of those strategies:

Some weeds have changed color so that they are indistinguishable from the crop they are hiding in.
Weeds that grew in dry ground, evolved to thrive in wet ground in rice fields that are flooded much of the crop season.
Some weeds became shorter to escape the mowing and harvesting of the agricultural crop.
Some weeds drop their seeds and go dormant before the crop is harvested and create seed banks that can sprout when conditions are more favorable for them.
Parasitic weeds wrap around their host and steal nutrients from them.

Some weed ecologists believe that a better understanding of the mechanisms used by weeds to foil our attempts to control them will enable us to devise better weapons against them. They believe that developing new herbicides and/or using more of them will always be a short-term solution.

For example, David Mortensen of Penn State is “investigating controlling weeds by planting crops like winter rye that can kill weeds by blocking sunlight and releasing toxins. ‘You want to spread the selection pressure across a number of things that you’re doing so that the selection pressure is not riding on one tactic,’ he said.”*

Regardless of what method is used to control weeds in the future, let’s consider the toxicity of the method the most important criterion for judging their effectiveness. Even if it kills fewer weeds, the least toxic alternative is the best alternative in our opinion.

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*Carl Zimmer, “Looking for Ways to Beat the Weeds,” New York Times, July 15, 2013.

Weeds: In Defense of Nature’s Most Unloved Plants

We would like to tell our readers about a charming little book about weeds, by the same name. Weeds: In Defense of Nature’s Most Unloved Plants, by Richard Mabey, contains an eclectic collection of information about the weeds of Britain, their origins, the history of their use–including as medicine, the role they have played in literature, and much more.

First, we venture a definition of weeds, though any definition is likely to be controversial. The concept of “weed” originated with agriculture, some 5,000 years ago in the Old World*, when man began to distinguish between those plants that are edible or otherwise useful and those that are not. And so, plants that are not perceived as useful or turn up in the wrong place, were defined by man as “weeds.”

It’s a shifting concept, because a plant that was useful historically, either because it was believed to be a cure for some malady, or was otherwise useful, might be replaced by some superior remedy. Such a changing concept of the value of particular plants is a central theme to the book as well as to the Million Trees blog. We often invite our readers to consider that much of the current interest in native plants is a horticultural fad that is likely to change in the future as it has in the past.

We also often question the designation of hundreds of non-native plant species as “invasive” in California, a designation that makes them a target for eradication. Mabey’s book about weeds helps us to put this designation into perspective. Britain obviously has a much longer history of trade with its neighbors on continental Europe, which increased the potential for the introduction of non-native species. Yet, despite Britain’s longer history of ecological globalization, Mabey tells us that only about one dozen species of plants are presently considered invasive in Britain compared to hundreds in California.

Rhododendron ponticum, one of only a dozen plants considered invasive in Britain. Wikimedia Commons

Mabey defends several of the non-native plants considered as invasive in Britain. He believes that some are merely responding to the disturbance of native vegetation by the activities of man. Nature hates a vacuum. When native vegetation is no longer adapted to the changed soil, water, and air quality conditions created by man, any plant that will grow in these new conditions is preferable to bare ground. Plants—including weeds—help the soil absorb rainwater into the ground which would otherwise run off the land, silting streams and causing erosion.

There is much food for thought in this little book. It invites us to compare our list of nearly 200 plants in California that have been officially designated as “invasive” to a short list of only a dozen plants in Britain. What accounts for this big difference? Different conditions or different attitudes? We don’t know the answer to this question, but we think it is a question worthy of consideration.

* Crosby, Alfred, Ecological Imperialism, Cambridge University Press, 2009