Garlic mustard has many culinary uses. It is primarily used raw because the flavor decreases when it is cooked. It adds a spicy flavor to salad dressings and quark or cream cheese mixtures.
From Wikipedia: “Alliaria petiolata is a biennial flowering plant in the Mustard family, Brassicaceae. It is native to Europe, western and central Asia, and northwestern Africa, from Morocco, Iberia and the British Isles, north to northern Scandinavia, and east to northern Pakistan and western China (Xinjiang).”
“In the first year of "growing", plants form clumps of round shaped, slightly wrinkled leaves, that when crushed smell like garlic. The next year plants flower in spring, producing cross shaped white flowers in dense clusters. As the flowering stems bloom they elongate into a spike-like shape. When blooming is complete, plants produce upright fruits that release seeds in mid-summer. Plants are often found growing along the margins of hedges, giving rise to the old British folk name of Jack-by-the-hedge. Other common names include Garlic Mustard, Garlic Root, Hedge Garlic, Sauce-alone, Jack-in-the-bush, Penny Hedge and Poor Man's Mustard. The genus name Alliaria, "resembling Allium", refers to the garlic-like odour of the crushed foliage. Some people give the species name Alliaria officinalis for this plant.”
Garlic mustard contains mustard oil glycosides, enzymes, carotenoids, saponins, and essential oil. It is also a good source of provitamin A and vitamin C.
“In 17th century Britain it was recommended as a flavouring for salt fish. It can also be made into a sauce for eating with roast lamb or salad. Early European settlers brought the herb to the New World to use as a garlic type flavoring, ...”
“The chopped leaves are used for flavoring in salads and sauces such as pesto, and sometimes the flowers and fruit are included as well. These are best when young, and provide a mild flavour of both garlic and mustard. The seeds are sometimes used to season food directly in France. Garlic mustard was once used medicinally as a disinfectant or diuretic, and was sometimes used to heal wounds.”
“Garlic mustard was once used as a medicinal herb. It has antiseptic, diuretic, and expectorant properties. It is believed to also be effective against asthma. In traditional methods, the leaves were used to make poultices to treat insect bites and worm infections.*”
As an invasive species:
“Garlic mustard was introduced in North America as a culinary herb in the 1860s and is an invasive species in much of North America. As of 2006, it is listed as a noxious or restricted plant in the US states of Alabama, Connecticut, Massachusetts, Minnesota, New Hampshire, Oregon, Vermont, West Virginia and Washington., and occurs in 27 midwestern and northeastern states in the US, and in Canada. Like most invasive plants, once it has an introduction into a new location, it persists and spreads into undisturbed plant communities. In many areas of its introduction in Eastern North America, it has become the dominant under-story species in woodland and flood plain environments, where eradication is difficult. ... Garlic mustard produces a variety of secondary compounds including flavonoids, defense proteins, glycosides, and glucosinolates that reduce its palatability to herbivores.”
“Garlic mustard was used as a culinary plant in the Middle Ages and the Early Renaissance as a culinary plant, but then as spices became less expensive and all social classes could afford them, it quickly was forgotten. Similar to wild garlic, modern cuisines are gradually rediscovering garlic mustard. However, garlic mustard is not as versatile as wild garlic because its flavor is less aromatic.*”
Note (italics): * = Translation from a German Wikipedia entry