Alliaria petiolata (M.Bieb.) Cavara & Grande

  • Family

    Brassicaceae (Magnoliophyta)

  • Scientific Name

    Alliaria petiolata (M.Bieb.) Cavara & Grande

  • Common Names

    garlic mustard, garlic-mustard, garlic mustard

  • Description

    Author: Scott A. Mori

    Description: Alliaria petiolata is an herbaceous biennial whose flowering form can reach 1 m (3.3 ft.) in height. The first year plants are a basal rosette of leaves that remain green throughout the winter. They develop into mature flowering plants the following spring. The lower, dark green leaves are reniform (kidney-shaped), while the stem leaves are alternate and deltoid. The basal leaf blades can be 6-10 cm (2.4-4 in.) long and wide, while the stem leaves are 3-8 cm (1.2-3.1 in.) long and wide, gradually decreasing in size as they go up the stem. The margins of the leaves are coarsely toothed. The leaves give off a strong garlic odor when crushed. The flowers of Alliaria petiolata are consistent with those of the mustard family. That is, there are four white petals arranged in a cross shape, and these are 5-6 mm (0.25 in.) in diameter. The flowers are arranged in terminal racemes. The cylindrical, shiny, black seeds are 3 mm (0.1 in.) in size and are contained in pods called siliques. These siliques are 2.5-6 cm (1-2.4 in.) long and 2 mm (0.08 in.) wide and contain 10-20 seeds. By June the plants are dead, often with the fruits still attached.

    Etymology: The species epithet refers to the long petioles.

    Common name: Garlic mustard

    Description: Alliaria petiolata is an herbaceous biennial whose flowering form can reach 1 m (3.3 ft.) in height. The first year plants are a basal rosette of leaves that remain green throughout the winter. They develop into mature flowering plants the following spring. The lower, dark green leaves are reniform (kidney-shaped), while the stem leaves are alternate and deltoid. The basal leaf blades can be 6-10 cm (2.4-4 in.) long and wide, while the stem leaves are 3-8 cm (1.2-3.1 in.) long and wide, gradually decreasing in size as they go up the stem. The margins of the leaves are coarsely toothed. The leaves give off a strong garlic odor when crushed. The flowers of Alliaria petiolata are consistent with those of the mustard family. That is, there are four white petals arranged in a cross shape, and these are 5-6 mm (0.25 in.) in diameter. The flowers are arranged in terminal racemes. The cylindrical, shiny, black seeds are 3 mm (0.1 in.) in size and are contained in pods called siliques. These siliques are 2.5-6 cm (1-2.4 in.) long and 2 mm (0.08 in.) wide and contain 10-20 seeds. By June the plants are dead, often with the fruits still attached.

    Distribution: From Maine to South Carolina, West to Minnesota, Iowa, Arkansas, Oklahoma, Utah, Washington and Oregon. It has been reported from all New England States.

    Ecology: It is successful in many types of habitats. It prefers moist, shaded areas, but can grow well at roadsides, edges of woods, along trails and in forest openings. Because of its shade tolerance it is one of few invasives that can be present and dominate a forest understory.

    Phenology: Flowers appear in the early spring (April-May); fruits are produced by May.

    Origin: Europe.

    Conservation status: Invasive species

    Notes: It is likely that settlers planted it in the United States for food and medicinal purposes. It was probably introduced into New England by planting as well, and then it dispersed across the landscape.

  • Floras and Monographs

    Alliaria petiolata (M.Bieb.) Cavara & Grande: [Book] Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.