Pl help me Flowers may seem beautiful to some, but beauty is in the eye of the beholder. Casual walkers in rural and urban areas in Alberta may enjoy the vibrant purple flowers of the purple loosestrife plant, but the trained eye of an ecologist sees the threat this invasive species poses.
Purple Loosestrife Invasion
Purple loosestrife was not always seen in and around Alberta. In fact, it wasn’t found anywhere in North America before the 1800s.
During the 1800’s, ships transporting goods around the world were sometimes without cargo for a time, particularly when they were heading to collect a new load. Wooden ships don’t balance well when they are empty, so when they were without a cargo, they were often filled with ballast instead.
How does this relate to purple loosestrife in Alberta? Well, purple loosestrife is a naturally-occurring plant in Europe and Asia, which means that their seeds may become mixed in with the soils found there. Ships sailing from Europe and Asia to North America without cargo often used soil as ballast to maintain the balance of the ships, and then dumped the soil when they arrived to pick up their cargo. It is believed that this dumped soil introduced the purple loosestrife species to Canada.
It may also be the case that early settlers brought purple loosestrife with them when they settled Canada’s west.

Purple Loosestrife: A Not-So-Welcome Introduction
So what’s the big deal about having purple loosestrife in Alberta? Well, purple loosestrife is not a species of plant that occurs naturally in the province- it is an introduced species. Organisms that don’t occur naturally in an area but are instead brought from elsewhere are categorized as introduced species.
Again, what’s the big deal about that? Well, organisms that are introduced to an ecosystem may become invasive - think: invader! An invasive species is defined as any organism that reproduces so quickly or grows so aggressively that it becomes a problem for the other organisms around it. Invasive plant species tend to outcompete local plants for resources such as sunlight, water and root space. In this way, invasive species can harm ecosystems by taking over, disrupting food webs and decreasing biodiversity.
Purple loosestrife has invaded local wetlands and is often found growing unchecked in other wet areas of the city. It flowers prolifically, producing millions of seeds each year. These seeds have many vectors of dispersal, for example, they may be blown to new places by the wind (aerochory), travel along with moving water (hydrochory), hitchhike in animals’ fur or be deposited in animal waste (zoochory), and even planted intentionally by humans.
Purple Loosestrife: Super-plant!
Purple loosestrife grows in clumps with a dense root system that extends underground like a living mat - it’s like a super villain, soaking up nutrients and taking over the space where other plants might grow. In wetlands, waterflow can be disrupted as waterways become clogged.
Over time, purple loosestrife becomes the dominant plant in an area and other plants disappear. This disrupts the food web because animals that only feed on the plants that disappear, disappear too. Once a plant disappears and the animals that feed on that plant disappear, there is a ripple effect along the food chain. Animals that can adapt to their food source disappearing by switching to a different food source will survive, but those that don’t adapt either move to a different habitat or die.

Waging War on Purple Loosestrife
In Alberta, purple loosestrife is classified as prohibited noxious, which means that it is not allowed to be planted and any plants that are found must be destroyed. In many Alberta cities, crews are sent out to dig out and destroy clumps of loosestrife that are reported.
Another way that purple loosestrife has been kept in check across Canada is through the use of biological controls (when one living organism is used to control another). Beetles such as the black-margined loosestrife beetle feed on purple loosestrife, so they are the plant’s natural enemies - perfect for biological control. Releasing the black-margined loosestrife beetle can reduce the purple loosestrife population in an area significantly. When an invasive species is controlled, often the original plants can re-populate and the ecosystem can return to a balanced state.

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