'Garlic mustard' (''Alliaria petiolata'') is a
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
India and western
China (
Xinjiang). It often occurs along the margins of
hedgerows, giving rise to the old
British folk name of ''Jack-by-the-hedge''. Other common names include ''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.

Close-up of Garlic Mustard flowers
It is a
herbaceous biennial plant (sometimes an
annual plant) growing to 30-100 cm (rarely to 130 cm) tall. The
leaves are stalked, triangular to heart-shaped, 10-15 cm long (of which about half being the
petiole) and 2-6 cm broad, with a coarsely toothed margin. In biennial specimens, first-year plants appear as a rosette of green leaves close to the ground; these rosettes remain green through the winter and develop into mature flowering plants the following spring. Others flower and complete their life-cycle in their first year. The
flowers are produced in spring and summer in buttonlike clusters, each flower small, white, with four petals 4-8 mm long and 2-3 mm broad, in the shape of a cross. The
fruit is an erect, slender, four-sided pod 2-7 cm long, called a
silique, green maturing pale grey-brown, containing two rows of small shiny black
seeds which are released when the pod splits open. A single plant can produce hundreds of seeds, which scatter as much as several meters from the parent plant. Depending upon conditions, garlic mustard flowers either self-fertilize or are cross-pollinated by a variety of insects. Self-fertilized seeds are genetically identical to the parent plant, enhancing its ability to colonize an area. Although water may transport the seeds, they do not float well and are not carried far by wind. Long distance dispersal is most likely aided by human activities and wildlife.
In Europe as many as 69 species of
insects and 7 species of
fungi utilize Garlic Mustard as a food plant, including the
larvae of some
Lepidoptera species such as the
Garden Carpet moth.
Cultivation and uses
The leaves, flowers and fruit are
edible as
food for
humans, and are best when young. They have a mild flavour of both garlic and mustard, and are used in
salads and
pesto.
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 and is listed as a noxious or restricted plant as of 2006 in the US states of Alabama, Connecticut, Massachusetts, Minnesota, New Hampshire, Oregon, Vermont and Washington.
[1]
The insects and fungi that feed on it in its native habitat are not present in North America, increasing its seed productivity and allowing it to out-compete native plants.
[2] A study published in 2006 concluded that Garlic Mustard harms
mycorrhizal fungi that some North American plants, including native forest trees, require for proper growth.
[3] Additionally, because
White-tailed Deer rarely eat Garlic Mustard, large deer populations may help to expand it by eating competing native plants. Trampling by browsing deer encourages additional seed growth by disturbing the soil. A complication in the eradication of Garlic Mustard is the long time span in which seeds may remain viable in the ground. Seeds stored in the soil can germinate up to five years after being produced.
[4]
References
1. http://plants.usda.gov/java/profile?symbol=ALPE4
2. Garlic mustard
3. Invasive Plant Suppresses the Growth of Native Tree Seedlings by Disrupting Belowground Mutualisms, Stinson KA, Campbell SA, Powell JR, Wolfe BE, Callaway RM, et al., , , PLoS Biology,
4. Garlic Mustard. Plant Conservation Alliance Alien Working Group. Accessed on 2007-07-14. [1]
External links
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Flora Europaea: ''Alliaria petiolata''
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Flora of China: ''Alliaria petiolata''
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Flora of Pakistan: ''Alliaria petiolata''
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Plants for a Future: ''Alliaria petiolata''
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Garlic mustard recipes
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U.S. NPS guide