The words “invasive plant” might seem self-explanatory, but in fact there’s a lot more to them than one might think. “With the development of Invasive Plant Councils in Canada in the last several years, people have started thinking beyond just invasive plants and weeds infesting crops,” says David Clements, professor of biology and environmental studies at Trinity Western University in B.C. ‘Backyard’ invasive plants are still something to avoid.
According to the Canadian Botanical Conservation Network, there are about 3,200 species of native plants in Canada and another 800 alien species that have “naturalized” here or become accustomed to living outside of cultivation. The Invasive Plant Council of B.C. defines invasive plants as alien species that have the potential to pose undesirable or detrimental impacts on humans, animals or ecosystems. They grow rapidly, spread quickly, are tolerant of tough conditions and can form dense patches.
Some plants deemed invasive might surprise the average gardener. Lily-of-the-valley, garlic mustard, hoary alyssum, English ivy and periwinkle all fit the bill in certain regions. What makes it difficult for most gardeners is that there is not one centralized list. Most provinces have some type of organization to educate the public about invasive plants. British Columbia, Alberta, Manitoba and now Ontario, for example, are all part of the Invasive Plant Council and supply detailed information regarding invasive plants for their province.
Why should we care?
Invasive plants are dangerous because they compete with and displace our native plant species, and they can potentially endanger plants that have been identified as being at risk, says Vivian Brownell, an invasive plants specialist with the Canadian Food Inspection Agency.