Invading garlic

Allirai petiolata (garlic mustard)

Garlic mustard is native to Europe, western and central Asia, and nothern Africa. As a biennial, in the first year of growth, plants form clumps of round shaped, slightly wrinkled leaves, that when crushed smell like garlic (hence the name...). The next year plants flower in spring, producing white flowers that release seeds in mid-summer.

Garlic mustard leaves are a great addition to wild salads, providing a mild flavour of both garlic and mustard. Garlic mustard was once used medicinally as a disinfectant or diuretic, and was sometimes used to heal wounds.

In the late 19th century garlic mustard was introduced in North America as a culinary herb, and since has gone on to become a very problematic invasive species. The success of garlic mustard, like that of other invasive species, is due to its lack of native competitors. Garlic mustard produces a variety of compounds that reduces its palatability to herbivores. Interestingly, in its native habitats, some herbivores have co-evolved to feed happily on the plants. But these insects and fungi that feed on it in its native habitats are not present in North America, and this leads to more garlic mustard seeds, allowing it to out-compete native plants. Even white-tailed deer, the scourage of many Eastern woodlands, don't eat the garlic mustard, preferring neighboring plants, which frees even more space for the garlic mustard to spread.