Ontario Weeds: Garlic mustard

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

Name: Garlic mustard, Alliaria petiolata (Bieb.) Cavara & Grande,

Other Names: alliaire officinale, A. officinalis Andrz. ex Bieb

Family: Mustard Family (Cruciferae)

General Description: Annual, winter annual or biennial, reproducing only by seed. It is distinguished by its broad leaves with rounded to coarse teeth, small white flowers and garlic-like odour.

Photos and Pictures

Garlic mustard.

Garlic mustard.

Garlic mustard. A. Rosette. B. Plant just beginning to flower. C. Top of older plant with many seedpods.

Garlic mustard. A. Rosette. B. Plant just beginning to flower. C. Top of older plant with many seedpods.

Stems & Roots: Stems up to 1m (40in.) tall, simple or little branched, smooth or with a few simple hairs

Leaves: Winter annual and biennial forms produce rosettes of leaves; these leaves varying from few to many, from kidney-shaped with a broad, rounded tip to narrower and ovate with a rounded or nearly acute tip, their margins toothed with shallow, rounded to deep, coarse, pointed teeth; lower stem leaves alternate, broad and kidney-shaped, to 10cm (4in.) wide and long, with coarsely toothed margins, becoming longer and narrower upward; upper leaves deltoid, 1-7cm (2/5-3in.) long and wide, or somewhat rhombic, with acute tip and coarsely toothed margins;

Flowers & Fruit: Flowers small, white, with 4 petals 3-6mm (1/8-¼in.) long and wide, the lowermost 1-3 flowers and seedpods may be in the axils of small leaves; seedpods (siliques) 0.4-5cm (1/6-2in.) long, spreading, and borne on short pedicels about as thick as the pods; their beaks slender, 1-3mm (1/25-1/8in.) long; seeds black, 3mm (1/8in.). The whole plant has a distinctive onion-like or garlic-like odour. Flowers from May to June.

Habitat: Introduced and naturalized from Europe, Garlic mustard is now found in moist woods, swampy areas and ditches and along roadsides and railway embankments throughout southern Ontario. It occasionally invades adjacent cultivated land.

Similar Species: Mature plants are distinguished from Wild mustard by their seedpods being more slender and having a slender beak that is never broad or flattened, and never containing an additional seed or two, and in some plants of Garlic mustard the lowermost 1-3 flowers or seedpods may be in the axils of small leaves, a characteristic it shares only with Dog mustard.

Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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