Alliaria petiolate

Description

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 growth, 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, skyut, 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. All parts of the plant, including the roots, give off a strong odor. In 17th century Britain, it was recommended as a flavoring 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, and as a good source of vitamins A and C. Its traditional medicinal purposes include use as a diuretic. The herb was also planted as a form of erosion control. The plant is classified as an invasive species in North America. Since being brought to the United States by settlers, it has naturalized and expanded its range to include most of the Northeast and Midwest, as well as southeastern Canada. It is one of the few invasive herbaceous species able to dominate the understory of North American forests and has thus reduced the biodiversity of many areas. Of the many natural enemies it has in its native range, several have been tested for use as biological control agents. Five weevil species from the genus Ceutorhynchus and one flea beetle were selected as candidates for preliminary testing in the 1990s. Since that time, those studying the candidates have narrowed the list to two-three weevils. Despite the demonstrated effectiveness of C. scrobicollis and C. constrictus in field testing, the importation and release of biological control agents such as those has been repeatedly blocked by the USDA's TAG (Technical Advisory) group. In particular, C. scrobicollis, which is monophagous and has been specifically studied since 2002, continues to be blocked, despite researchers' many petitions for approval. It is currently estimated that adequate control of garlic mustard can be achieved by the introduction of just two weevils, with C. scrobicollis being the most important of the two. Not one of the roughly 76 species that control this plant in its native range has been approved for introduction as of 2018 and federal agencies continue to spend millions on other, less-effective and more problematic, forms of control, such as chemical herbicides.