Most invasive plants that we consider pests are not native to Canada. According to the Canadian Botanical Conservation Network , there are 800 species of plants that have been naturalized or have been accustom to growing out of cultivation. Of those 800 plants, some have become annoying weeds, but others, like garlic mustard, have become of deadly invaders.
Garlic mustard has been plaguing botanical gardens, arboretums and natural habitats across the country for years. Now, as this plant spreads, home gardeners are dealing with this destructive weed.
What is it?
Garlic mustard (Alliaria petiolata) belongs to the mustard family. Also known as Jack-in-the-bush, sauce-alone, hedge garlic and poor man’s mustard, this plant is a shade-tolerant biannual that can be found thriving in woodlands and along riverbanks. In the first year of growth, plants form low clumps with round leaves. During the second year, white flowers are produced on terminal racemes, meaning the flowers are arranged singly along a stalk. When crushed, the bright green leaves smell distinctively of garlic.
Why is it such a problem?
Considered the ‘purple loosestrife’ of woodlands, garlic mustard steals light, moisture and nutrients from other native plants. Its aggressive, rapid growth allows it to form a dense carpet of foliage, blocking light from other low-growing plants, including tree seedlings.
According to the Committee of the Status of Endangered Wildlife in Canada, garlic mustard has threatened the survival of two species of woodland plants. The wood poppy is classified as endangered and the wood aster’s status is threatened. The plant has also been linked to the decline of the trout lily, trilliums and other native wildflowers in Canada.