The Green Medium is an Emerald Award-winning, youth-run blog that seeks to innovate how we discuss and inform ourselves on environmental concerns.

Invasive Plants: That's A Lot Of Purple Loosestrife

Purple Loosestrife


You might be wondering “what is purple loosestrife?” Well, purple loosestrife is a plant that can be found in generally wet environments throughout Alberta, and grows to be fairly tall with gorgeous purple flowers. I know what you’re thinking. Who cares? It sounds like a nice organism. Unfortunately, purple loosestrife is an invasive plant. Here and in other parts of Canada, it is capable of dominating wetland areas and altering ecosystems. So why is it invasive, what makes a plant invasive, is there any real problem if something invades, and why don’t I move on from this inquisitive digression?

Invasive vs Introduced

Firstly, I should point out that an invasive species is different from an introduced species. Let’s say you’re from Uruguay, and you’re taking a boat to Canada. For mysterious reasons that you’d rather not share, you have decided to bring a whole bunch of a native Uruguayan plant species and its seeds. So you get to Canada, and inevitably some seeds slip out somewhere, you plant a couple plants, and eventually, it’s in the natural environment. This is an introduced species, all the way from Uruguay. Is it invasive though? That depends. If your plant begins to dominate in its environment, disturbing local communities and ecosystems, then it is considered invasive.

Becoming Invasive: A Short Story

Why though, do some introduced plants become invasive? Not all of them do, and sometimes the same plant may be invasive in one place and non-invasive in another. The truth of the matter is that the reality of the situation is that biology is complicated and rather messy. Firstly, a plant may become invasive due to a lack of enemies, who in this case are herbivores. Imagine a type of grass native to Europe called Rachel. Throughout Europe, there is a particular insect called Cindy that feeds on Rachel. Cindy has evolved mechanisms to tolerate the toxic chemicals released from Rachel’s leaves when they get damaged. Rachel is a successful species but is unable to completely take over and outcompete other plants due to this herbivory. Now, what if Rachel is introduced to the USA? At this point, there is an important question that must be asked. Is Cindy in the USA? What if Cindy is solely European. Who is going to eat Rachel’s leaves? The American insects have not been around Rachel, and have not evolved ways to deal with her toxins. Thus, Rachel could easily become invasive.

Becoming Invasive: Why It’s Not Straightforward

There are various other reasons why invasiveness occurs or doesn’t occur. Sometimes diseases and parasites that normally affect a species are unable to survive in a different environment. Climate can have an effect, as well as the other plants present. Sometimes local plants simply cannot compete with a new species. The list of factors at play is pretty long. Sometimes an introduced species that hasn’t been causing any problems for multiple years may eventually become invasive. It is thus quite difficult to predict and prevent all of this. So then, is there any point in trying? Really, it just seems like a big mess. What’s the big deal anyway? So what if plant community structures change. Big deal. Actually yes, big deal is right.    

The Consequences Of Invasive Species        

These invasive plants present a great threat to local plant life and ecosystems in general. Because of all this, they present a threat to human beings, including Canadians and Uruguayans. We use a variety of ecosystem services that depend on, surprise surprise, ecosystems. These include food, water, avoiding floods, plant materials from a range of species including natives, plant biomass for energy, carbon sequestration, animals and more. Invasive plants have the potential to throw a big fat wrench through all of this. Without the human side, plant biodiversity is endangered, and thus so is biodiversity of other organisms that interact with and depend on plants. Crazy stuff.  

What You Can Do About It:

Travelling and Being In Nature

You can help prevent the further success and appearance of invasive plants. If you’re travelling, and you’re going to be spending a lot of time outdoors, be careful not to bring plant material such as seeds back home. Accidentally transporting species across countries and continents could have an impact. It’s also important to keep these things in mind when hiking or camping. Plants can spread easily through gear and clothing. You might be thinking “Yeah, but I’m just camping over in the Rockies!”, but the Rockies are a significantly different environment with different flora, overall biodiversity, and climate. A plant could become more invasive in some parts of the province than others.  


Anyone here like to garden? It’s a nice thing to do, and you can become an even better gardener by considering invasive plants. Check to see which plants are listed as invasive in your region, and avoid planting those in your garden. That’s a pretty good start, but it doesn’t mean that they won’t show up on their own. If they do, get rid of them. This does not mean hurling them out into the woods, in fact, that makes things worse. The Alberta Invasive Species Council suggests that they should be secured in a bag and shipped off to a landfill. I think another fun option is to dry them (make sure they’re dead) and keep them somewhere inside as art.

Promoting Native Plants

You can also grow native plants. Wait, what? Native plants date back to sometime a very long time ago in their particular region. Alberta has lots of lovely native species. These plants are an important part of local ecosystems and communities, and often are put at risk by the spread of invasives. Well, with that clever little conclusion, I am going to conclude this piece. Make sure to read my next entry which will feature the Alberta Native Plant Council. Thank you for reading.

Invasive Plants: The Alberta Native Plant Council

Invasive Plants: The Alberta Native Plant Council

Invasive Plants: An Introduction

Invasive Plants: An Introduction