When I drove into the Walmart parking lot, the colorful flowers caught my eye. I could see dozens of potted plants lining the side of the building. My steady pace crept to a crawl as I peered through the fence at the green foliage within the Walmart Garden Center. The majority of the plants I could see looked like common garden ornamentals. Things like daisies and petunias. Beautiful in an artificial way and harmless in their appearance. And personally, not my favorite types of flowers.
I parked my car, proceeded into the store, and accomplished my errands. All the while, those flowers kept coming to my mind. I could not help but wonder if hidden within the Garden Center; there might not be an element of danger to purchasing those plants. An ecological threat that far too few people are aware of.
An invasion that starts in your backyard
The origin story for numerous invasive plants begins within a backyard or with a visit to the local garden center. BBC Gardeners’ World Magazine reports that many gardeners are unaware that their yards can serve as ground zero for the start of an invasion. BBC Gardeners World Magazine States that, gardeners are often aware of only the most invasive plants. Plants, such as garlic mustard, which are heavily censored by government agencies for their potential to cause environmental damage.
Tragically, many gardeners are unaware that ANY ornamental garden plant can become an invasive plant. Simply because ornamental plants, especially plants imported from other countries, often arrive at environments free from their endemic natural predators. In a new world free from the endemic limiting factors that control their population in the wild ( i.e., insects, fungi, etc.), these plants are free to grow as wild and untamed as they please.
For every well-known botanical invader, there maybe twenty or thirty other typical garden plants with the same capacity to become as ecologically damaging as their invasive plant-labeled counterparts. Too often, these plants are readily available to the public through nurseries and garden centers.
As Steph Coelho remarks in his article 20 Invasive Plants Sold at Nurseries, You Should Never Use, “you’d be surprised how many common plants are trouble masquerading as something beneficial.”
An unassuming garden plant turned environmental invader
No better example exists for an unassuming garden-plant-turned-environmental-invader than a popular garden herb; pennyroyal. Pennyroyal (Mentha pulegium), has been grown for centuries as a medicinal plant in Europe and North America. In Growing Pennyroyal: How to Grow Pennyroyal Herb, Bonnie Grant states that pennyroyal possesses square stems with oppositely arranged leaves.
Pennyroyals’ reliable aromatic quality helps to solidify its place within the mint family, Lamniaceae. Although used to treat a variety of ailments and act as an insect repellent, WebMD warns that this plant is highly toxic and can cause liver damage when overconsumed.
Today, As Jamie McIntosh from the Spruce states, pennyroyal is often utilized as a ground-cover or accent plant as ” { pennyroyal} is very easy to grow{ and} it’s profuse lavender flowers attract butterflies. {It’s} spreading habit {quickly} fills in bare spots in the garden or container”.
Unfortunately, this plant’s capacity for being a fast-growing and robust perennial, a common feature in the mint family, according to Marie Lanotti of the Spruce, can be detrimental for many gardeners.
Pennyroyal’s ability to tolerate a wide variety of environmental conditions, especially wet environments, and grow through rhizomatous growth make it likely to crowd out other plants within the garden. Pennyroyals tendency to thrive in moist environments also enables it to be the silent ecological invader that it has become.
Documented in Washington, Oregon, and California, pennyroyal thrives in disturbed moist places, as documented by the UC Weed Research and Information Center at the University of California Davis. The California Invasive Plant Council classifies penny-royal as a moderately invasive plant, whose propensity to thrive in moist and wet environments enables it to colonize sensitive wetlands.
The frightening fact, according to the California Invasive Plant Council, is that “the ecological impacts of pennyroyal are not well documented. Though it prospers in habitats that were once dominated by native plants, suggesting that it may have displaced some species.”. We will never understand its full potential to cause harm until we can assess the ecological and economic damage caused by this plant.
Despite the evidence that pennyroyal has already invaded natural areas within the Western United States, pennyroyal resides within most major garden centers and nurseries. Few people are probably aware that this plant is an invasive species.
I only became aware of pennyroyals evolution into an ecological invader only recently. After seeing far too many wetlands and wetland meadows become monopolized by this aromatic invader, my concern has only continued to grow. This concern was dominating my mind as I drove into the Walmart parking lot that day.
Pennyroyal may be an invasive plant, but at least it is one where we are starting to recognize its true nature. Too many potential invaders are making their way into people’s backyards—plants that may become the next threat to the integrity and wholescale health of our planet.
Pennyroyal, I have come to see, is a reminder that any plant, when placed within the right environment, can become a perfect storm that threatens the very future of the natural world.
