Invasive Plants of the Eastern United States Home   |   About   |   Cooperators   |   Statistics   |   Help   |
The Bugwood Network
Join Now   |    Login    |    Search    |    Browse    |    Partners    |    Library    |    Contribute

Garlic Mustard
Alliaria petiolata (Bieb.) Cavara & Grande

International Code - ALPE4
FIA survey code - 6002

Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS–62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.

acrobat version

Plant. Cool-season biennial forb with a slender taproot found in small to extensive colonies. Basal rosettes of leaves in the first year remaining green during winter and producing one to several 2- to 4-foot (60- to 120-cm) tall flower stalks in the second year, and then dying after seed formation in midsummer. Dead plants remaining standing after June as long slender seedstalks with many upturned thin seed capsules and a characteristic crook at the stalk base. A faint to strong garlic odor emitted from all parts of the plant when crushed, becoming milder as fall approaches.

Stem. Erect, slightly ridged, light green, hairless above and hairy below. One to several stems from the same rootstock.

Leaves. Early basal rosette of kidney-shaped leaves and later alternate heart-shaped to triangular leaves, 1.2 to 3.6 inches (3 to 9 cm) long and 1 to 4 inches (2.5 to 10 cm) wide. Margins shallow to coarsely wavy toothed. Tips elongated on stem leaves. Petioles 0.4 to 3 inches (1 to 8 cm) long and reduced upward.

Flowers. April to May. Terminal, tight clusters of small white four-petaled flowers, each 0.2 to 0.3 inch (5 to 7 mm) long and 0.4 to 0.6 inch (10 to 14 mm) wide. Flowering progressing upward as seedpods form below.

Fruit and seeds. May to June. Four-sided, erect-to-ascending, thin pod, 1 to 5 inches (2.5 to 12 cm) long and 0.06 inch (1.5 mm) wide. Initially appearing to be stem branches that are alternately whorled along the stalk. Green ripening to tan and papery, exploding to expel tiny black seeds arranged in rows.

Ecology. Occurs in small to extensive colonies on floodplains, under forest canopies, and at forest margins and openings. Shade tolerant. Capable of ballistic seed dispersal of up to 10 feet (3 m). Spreads by human-, animal-, and water-dispersed seeds, which lie dormant for 2 to 6 years before germinating in spring. Experiences year to year variations in population densities. Allelopathic, emitting chemicals to kill surrounding plants and microbes.

History and use. Introduced from Europe in the 1800s and first sighted as an escaped weed in 1868 on Long Island, NY. Originally cultivated for medicinal use, but no known value now.

Photo by J. Randall

Photo by J. Randall

Photo by J. Shimp

Photo by J. Meade

Photo by H. Wilson

Photo by J. Shimp

Photo by S. Ross

States with suspected infestations are shown in gray.

Recommended control procedures:

  • To control two generations, thoroughly wet all leaves with a glyphosate herbicide as a 2-percent solution in water (8 ounces per 3-gallon mix) during flowering (April through June). Include a surfactant unless plants are near surface waters.
  • In locations where herbicides cannot be used, pull plants before seed formation. Repeated annual prescribed burns in fall or early spring will control this plant, while “flaming” individual plants with propane torches has also shown preliminary success.

[  Home  ]   [  Contents  ]

USDA Forest ServiceUSDA APHIS PPQ The Bugwood Network University of Georgia is a joint project of
The Bugwood Network, USDA Forest Service & USDA APHIS PPQ.
The University of Georgia - Warnell School of Forest Resources and
College of Agricultural and Environmental Sciences - Dept. of Entomology
Last updated on Wednesday, November 05, 2003 at 01:37 PM
Questions and/or comments to the