Garlic mustard Invasive garlic mustard can take over forests, harming native understory species (Photo by NCC) No friend to our forests Garlic mustard , a highly invasive plant, has been spotted on Nature Conservancy of Canada (NCC) properties across Ontario. Brought to North America in the 1800s, this invasive alien plant is now spreading across the continent at a rate of 6,400 square kilometres per year — that's an area 10 times the size of Toronto! The success of garlic mustard is multi-faceted. Aside from having no natural enemies in North America, garlic mustard is an early riser. It takes advantage of the open canopy of springtime deciduous forests and the first rays of sunlight after the winter snow has melted, getting a head start on the native plants. Garlic mustard can change a forest's composition over time, creating a more favourable environment for itself, while driving other species out of the understory. This can even impact what trees grow in the forest, as garl