Terrestrial invasive species

Nature

Most of these invasive plant factsheets are created from the booklet Minnesota invasive non-native terrestrial plants, an identification guide for resource managers.

Check the additional resources and herbicides table for more information.

Garlic mustard (Alliaria petiolata)

Garlic mustard (Alliaria petiolata)

Description:

Appearance: Biennial herbaceous plant with weak single stems 12 - 36" high in its second and flowering year. Only plant of this height blooming white in wooded environments in May.

Leaves: Round, scallop-edged, dark green; first year, rosettes of 3 or 4 leaves; second year plants have alternate stem leaves. Leaves and stems smell like onion or garlic when crushed.

Flowers: White, small and numerous, with four separate petals. Each plant has one or two flowering stems on second year plants.

Seeds: Slender capsules 1-2 1⁄2" long, containing a single row of oblong black seeds. Seeds are viable in the soil for 5 years.

Roots: White, slender taproot, "S"-shaped at the top.

Ecological Threat:

  • Garlic mustard spreads into high quality woodlands upland and floodplain forests, not just into disturbed areas.
  • Invaded sites undergo a decline on native herbaceous cover within 10 years.
  • Garlic mustard alters habitat suitability for native insects and thereby birds and mammals.
  • This European exotic occurs now in 27 midwestern and northeastern states and in Canada.
  • Garlic mustard is a MDA Prohibited noxious weed (Controlled List) in Minnesota.

 

Control Methods:

Mechanical
Pulling in areas of light infestations

Flowering stem cutting at ground level

Prescribed burning if there is enough fuel to carry the flames

Chemical
Spot application of 2% glyphosate in early spring or late fall when native plants are dormant

 

Native Substitutes:

More information