garlic mustard

Alliaria petiolata (Bieb.) Cavara & Grande

Description from Invasive.org

Appearance

Alliaria petiolata is an herbaceous, biennial forb. First year plants are basal rosettes which bolt and flower in the second year. Plants can be easily recognized by a garlic odor that is present when any part of the plant is crushed.

Foliage

Foliage on first year rosettes is green, heart shaped, 1-6 in. (2.5-15.2 cm) long leaves. Foliage becomes more triangular and strongly toothed as the plant matures.

Flowers

Second year plants produce a 1-4 ft. (0.3-1.2 m) tall flowering stalk. Each flower has four small, white petals in the early spring.

Fruit

Mature seeds are shiny black and produced in erect, slender green pods which turn pale brown when mature.

Ecological Threat

Alliaria petiolata is an aggressive invader of wooded areas throughout the eastern and middle United States. A high shade tolerance allows this plant to invade high quality, mature woodlands, where it can form dense stands. These stands not only shade out native understory flora but also produce allelopathic compounds that inhibit seed germination of other species. Alliaria petiolata is native to Europe and was first introduced during the 1800s for medicinal and culinary purposes.

Resources

• Best Management Practices - Ontarios Invading Species Awareness Program
• A Field Guide for the Identification of Invasive Plants in Southern Forests - USDA Forest Service
• Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
• Southeast Exotic Pest Plant Council Invasive Plant Manual - SE-EPPC
• Pest Alert - USDA Forest Service
• Weeds Gone Wild: Alien Plant Invaders of Natural Areas - Plant Conservation Alliance
• Element Stewardship Abstract - The Nature Conservancy
• Fire Effects Information System - USDA Forest Service
• Weed of the Week - USDA Forest Service
• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service
• Fact Sheet - Ontarios Invading Species Awareness Program

Selected Images from Invasive.org

View All Images at Invasive.org

Infestation
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Foliage first year leaves
Jil Swearingen, USDI National Park Service, Bugwood.org
Additional Resolutions & Image Usage

Plant(s) in flower
David Cappaert, , Bugwood.org
Additional Resolutions & Image Usage

Plant(s) 1st year rosette
Tom Heutte, USDA Forest Service, Bugwood.org
Additional Resolutions & Image Usage

Plant(s) in flower
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Foliage 1st-year basal rosette. Clayton County, IA
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s) Long,thin, upright seed pods (siliques). Martin County, KY
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Plant(s) in flower
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Flower(s)
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Infestation
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Plant(s)
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Plant(s) in flower
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Control After control. Part of a before/after volunteer hand-pull control series. See image #2132001 for before image
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Control Before control. Part of a before/after volunteer hand-pull control series. See image #2131100 for after image
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Infestation Understory incursion
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Seed(s)
Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org
Additional Resolutions & Image Usage