Seeing Invasive Plants In A New Light

It has been a while but I am back, now as a senior of E.O. Smith's Depot Campus.  Debra has been gracious enough to allow me to publish my own senior paper here on her website for anyone to read.  This paper wasn't just written for the credit, the ultimate purpose was the promotion of conversation pertaining to the usage of commonly seen plants from ecologically disturbed areas all around us.  I hope you appreciate the reading starting below, feel free to comment thoughts and share to anyone else who'd be interested.  

Seeing Invasive Plants In a New Light

In 2014, National Geographic magazine published an article by Emma Marris titled "It's Time to Stop Thinking That All Non-Native Species Are Evil", discussing the fact that simply because a plant or organism is artificially introduced into an ecosystem, it is not always detrimental (Marris 1).  Nevertheless, the majority of scientific research is devoted to eradicating invasive plant species as a primary defense to propagation, yet scientists are losing the battle against these hearty, fast growing nemesis, a battle all but lost and extremely expensive to carry out once the species has become well-established.  In fact, of the thirty planned plant eradication efforts undertaken in the Galapagos Islands since 1996, only four have been successful (Davis 154). Recent studies suggest that effects of invasive species should not be biased towards simply eradication and should instead focus on the positive impacts of invasive species for assessment and management of ecosystems as well as for medicinal practices.  There are countless multi-faceted invasives species that could be mentioned, but this essay will focus on five plants specifically. The first being Japanese Barberry, a shrub that is generally observed within overgrazed meadows, backyards, and damaged areas, quite common place here in New England. Secondly, I will be talking about the beneficial aspects of Houttuynia, another species with invasive characteristics, but still nonetheless useful in the treatment of Lyme and other ailments. In addition to these, this paper will also talk about the benefits of Garlic Mustard, Japanese Knotweed via oral administration and to Mugwort - a plant whose medicinal effects are not limited to ingestion, that can also be useful through topical exposure.   While it may seem beneficial to eradicate these invasive plant species entirely, it would be better for us to figure that since the plants are living so vigorously that they must be here for a reason; they must provide some use to us. Our planet so generously provides an ideal amount of resources for sustainable life, why not treat the Earth with the care, respect and awareness it deserves? This idea resonates with me as I have never really been the type of person who is ok with wasting resources, or having a lack of care for my environment. Call me a hippy, I would rather be ever-mindful of how I treat and interact with the planet in order so that my stay here is long lived.

Though invasive species is by definition an alien species whose introduction does, or is likely to cause economic or environmental harm or harm to human health, not all invasive species are unwanted. There are many cases where scientists have demonstrated evidence for beneficial attributes of invasive plants.  For example, in California, monarch butterflies prefer to spend their winters in the branches of the eucalyptus, an invasive exotic tree transplanted to the state more than 150 years ago and it was only since this time that monarchs have migrated to this region (Vane-Wright 183). In a 2016 New York Times article, author Erica Goode illustrates the pervasive assumption that “what hails from elsewhere is inherently bad, these researchers say, rests more on xenophobia than on science” (Goode 1). She recounts her interview with Ken Thompson, author of “Where Do Camels Belong: Why Invasive Species Aren’t All Bad, where he states that  “invasion” is just another word for “change” and that as a philosopher might say, “the only thing that is certain is that more change is to come” (Goode 1). Plants and animals around the world are more similar than they once were, as globalization has, accidentally or intentionally, just moved exotic species from one place to another. Goode also addresses the idea that although one invasive species may overtake a certain plant community that “as more species migrate, new quandaries are likely to arise. And as the human population increases, driving more animals and plants toward extinction, a species’ second home may be the only one it has” (Goode 1). Ecologist today must therefore examine the cost benefits of plants like the Japanese Barberry, one of the most hated invaders and instead decide how to live and embrace living with these incredible hearty plants, that just happened to come from somewhere not inherently connected to the community beforehand.  

Shrubs, like the Japanese Barberry, Berberis thunbergii are also considered invaders or an alien species both for their growing characteristics and because they were imported to North America. Barberry is a non-native invasive shrub that was first introduced to the continental U.S. in 1875 as an ornamental plant based solely off its desirable appearance spectacularly displayed in autumn when the leaves turn from green to yellow to bright red before eventually falling off to reveal their sharp spines protruding from the base of each node.  The plant is known particularly for its opportunistic attributes - it will thrive in an array of ecosystems such as open fields, woodlands, wetlands, and most of all disturbed areas. This is all due to its extreme adaptability in that it is both shade tolerant and drought resistant a feature particularly useful in regions of the U.S. like CA and NV that have been plagued by severe water shortages. However, care must be taken as it is also known to degrade and dominate functional woodland ecosystems where there is competition for the beams of sunlight that are able to penetrate the tree canopy.  Additionally, researchers like UConn Professor Tom Worthley, have found that tick borne diseases are greatly inhibited by controlling growth of Barberry, a primary example why control of this species invader is necessary (Foran 1). Nevertheless, even though this invasive species has become an increasingly unwanted plant, people should still consider that Japanese Barberry contains many active constituents including Berberine that has many therapeutic effects and supports why this plant cannot be simply labeled as detrimental to ecosystems. Berberine is used to alleviate dysentery and diarrhea caused by food poisoning, in addition to traveller’s diarrhea.  Additionally, Berberine is an alkaloid and both alkaloids and extracts of alkaloid‐containing plants have been used throughout human history as remedies for common ailments (Fester 1). There are an array of ailments that have and can be treated by alkaloids, such as swelling, inflammatory conditions, infections, skin diseases, gastrointestinal ailments, cardiovascular problems, liver problems, and respiratory tract conditions (Kulkarni 317). Berberine and its derivatives act as anti-inflammatory and anti-tumor agents in the digestive system for the development of this natural product as novel anticancer drugs with anti-inflammation activity (Zou 2017). Finally, it is also interesting to note that the Berberine component of plant alkaloids is currently being explored in treatment of neurological disorders such that occurs during the secondary phase of Lyme disease (Kulkarni 317, Buhner 339).  Therefore the plant that is responsible for lodging the ticks themselves, may prove to be an effective treatment to Lyme. Therefore, like many others “invasive species”, careful consideration of benefits versus detrimental effects of eradicating this plants needs to be further studied.

Houttuynia cordata or “chameleon”, is another plant considered to be an invasive species.  It is a creeping aromatic medicinal herb found natively in Northeast India, and China. According to the Invasive Species Specialist Group, Houttuynia cordata is a perennial plant that was introduced as an ornamental for water features in the late '80s but has become an invasive nightmare feared to be a huge risk to native habitats (Houttuynia Cordata 1). It has a high reproductive and vegetative growth rate and quickly overtakes the gardens where it is planted. Control of Houttuynia cordata is difficult as it reproduces by both seeds and rhizome fragments and it is recommended that all “uprooted plant material should be disposed of by incineration or taken to an official transfer station or landfill site [equipped to handle invasive plant material]” (Lewis 4). There are two variations of this species, the Japanese which has an aroma of citrus, and the Chinese which has a scent reminiscent to coriander.  As far as the medicinal benefits, they are countless, including blood purification, anti-inflammatory activity, antibacterial activity, anaphylactic inhibitory activity, anti-allergic activity, antidiabetic activity, antioxidant activity, as well as antiviral activity specifically for herpes simplex virus (Kumar 22). Besides being used for ailments such as dysentery, plants are also crushed and spread in chicken coops to keep away flies in India (Changkija 219). The plant is administered by several methods including raw consumption, leaf juice, young plants are cooked as a pot-herb either to be cooked, or to make a decoction (Kumar 24). Houttuynia cordata is therefore medicine you grow in your backyard for free, a great reason for not destroying this plant.

Japanese knotweed (Polygonum cuspidatum), mugwort (Artemisia vulgaris) and garlic mustard (Alliaria petiolata) have become particularly problematic in the Northeastern U.S. in recent years in both agricultural, roadside settings and parks (Weston 2005).  Although a nuisance to some, city dwellers enjoy foraging for for both plants during strolls through New York’s Central Park, taking advantage of the easy access and to these trendy new culinary sensations. Knotweed has a tasty lemon flavour can be sauteed it with olive oil and sesame seeds in combination with green beans while mugwort is used as a slightly bitter addition to salads or a rub on meats. The biennial garlic mustard can be identified as edible when it’s coarsely toothed leaves,1-3’ high have long-stalked blooms white flowers, ¼-⅓” wide, smelling of garlic when crushed (Newcomb 138). Author Marie Viljoen describes vegetation in Central Park as “higher up are swathes of invasive daylilies, garlic mustard, Japanese knotweed and field garlic ... (and recommends learning) to recognize ubiquitous mugwort: it may be a pest but it’s the best pest for a nest in the pot. Sorry. Spring fever” (Viljoen 1).These “invaders” also have other therapeutic uses as Japanese knotweed helps in treatment for cough, hepatitis, jaundice, burns and snake bites and recent pharmacological and clinical studies have indicated that Japanese knotweed has “antiviral, antimicrobial, anti-inflammatory, neuroprotective, and cardioprotective functions” (Zhang 1). Mugwort, easily spotted by their leaves with pointed lobes, white-woolly beneath” (Newcomb, 428) has therapeutic uses including treatment for epilepsy (Buznego 847), as a remedy to insomnia, relief to menstrual pain/cramps, stomach pain, indigestion, as well as a stimulant for irregular menstruation (Lee 3325).  Since its been shown to stimulate menstruation it should be avoided by pregnant women, as it will induce miscarriage. Apart from its therapeutic effects, one must still consider its invasive and seemingly negative growth characteristic, which is that its roots inhibit the growth of some below-ground fungi that many native plants require, reducing the ability of tree seedlings to survive in a sea of this plant. However, new research has “found that invaded areas have a greater diversity that of fungi, perhaps because the dominant ones disappeared” (Roman 1) and there is a strong correlation between biodiversity and stability of ecosystems (Loreau 106). Organic growers may consider accepting garlic mustard in planters near their gardens to thwart deer who rarely feed on it. In the wake of devastating wildfires in the Northwestern U.S., garlic mustard may even be considered as a plausible form of ground cover, and in turn would provide erosion control thanks to its vigorous root growth. As more and more people attempt to both live and eat in an ecologically friendly manner, these three plants are standouts towards that ideal.

It is time to reconsider vilifying non-native species for driving what are considered “native” species to extinction and condemning them as destructive polluters of “natural” environments. Cornell University ecologist David Pimentel estimates that the U.S. spends around $120 billion each year to control invasive species. Given that some of these species like garlic mustard can be quite palatable, why not follow the idea, “If you can’t beat ’em, eat ’em.” (Ohlson 6).  Many of these plant species are out of control because they have no natural predators, so why not convince the fiercest predator of all—human beings—to make good use of them as food and therapeutic remedies? If there’s one thing research into this subject can teach someone, it is not to judge a species on its place origin. If a plant has nutritional or medicinal gain, place those attributes over potentially aggressive growth habits, with discretion of course.

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