Let us be clear about this from the outset: garlic mustard (is an invasive—a marching, pesky alien that, in certain areas and situations, spreads easily and forms a near monoculture along shady riverbanks and their wooded floodplains, on the sides of damp forest trails and roadways, anywhere that the light is dimmed and the soil moist. Because a single biennial plant produces thousands of seeds, and grows aggressively in the cool dampness of mid-spring, garlic-mustard severely threatens a number native species—including concurrent ephemerals such as bloodroot, Dutchman's breeches, hepaticas, toothworts, and trilliums, to name just a few, along with any insects and invertebrates that depend upon them.
Yet the plant's single best weapon, the reason for its success, is a lack of natural enemies. Nothing much seems to like eating garlic-mustard, including whitetail deer. In Europe, the plant's original home, garlic-mustard is not invasive because it is relished by upwards of three dozen different species of insects; here in North America…zip, nada, not one bug finds it palatable—at least not enough so to make any difference to its unwanted expansion.
The irony is that garlic-mustard was brought to this country for food and as a medicinal herb by early settlers. The fact is, the young leaves of garlic-mustard—which tastes, as you might imagine, of both garlic and mustard—makes a good addition to salads, stir-fries, and sauces. I've not yet done so, but garlic-mustard is said to make an excellent pesto for pasta, baked potatoes, roasted veggies, even over broiled fish.
Garlic-mustard's tiny (1/3 to 1/4 inch) flowers, grown in clusters atop a stalk that's anywhere from 1–3 feet tall, are nevertheless undeniably lovely. Pale white blooms that look like miniature cross-stitches amid the darker greenery.
Like so many other invaders we've introduced with good intentions, garlic-mustard has not only turned on us—it's settled in for the long haul, unlikely to ever be eradicated. The best we can do is learn how to remove the plants, and to do so whenever and wherever possible. And if you believe that vengeance is sometimes best served up for dinner, you'l be tastily rewarded.