Garlic Mustard: Accurate Identification

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- Garlic mustard as an invasive or basis member of the mustard family, originating from Europe and parts of Asia.

Earliest known reports documented growing on long Island, New York in 1868.

It is believed to have been brought over by early European colonizers and used for medicinal purposes and food.

Garlic mustard has a biennial lifecycle taking two years to fully mature and produce seeds.

The first year is a ground level or basal year and the second year a reproductive or bolt year when it goes to seed.

Garlic mustard's vigorous reproduction has enabled it to spread from coast to coast where it displaces native plants and communities with moist rich soils.

Garlic mustard is frequently found growing on river flood plains and woodlands along field edges and in openings.

It is shade tolerant and often spreads from field edges to mature undisturbed forest under stories.

A prolific cedar it can form dense mono-cultures reducing native plant biodiversity.

In the first or basal year of growth, the leaves are kidney bean shape with rounded teeth along the edges and highly variable in size.

Each leaf is usually less than four inches across and the plants are no taller than eight inches in height.

The least form of basal rosette meaning all the leaves on a single plant emerge from one central underground stem.

At this early stage, the leaves and stems produce a garlic odor when crushed which tends to fade as the plant ages.

In early spring of the second or bolt year of growth, the stock develops from the basal rosette rapidly elongating up to three feet in height.

The leaves become more heart or triangular shaped and are two to four inches across the pointed irregular teeth along the edges.

The plants produce a flower head at the upper most growing tip of the stock where clusters of four peddled cross shaped white flowers emerge from late April through June.

By summer, the flowers are replaced by long narrow stems called solics each containing one row of oblong brown to black seeds.

There's wide variability in solic size and number of pods.

At first green, the solics become brown and brittle when ripe in mid to late summer a stage referred to as seed shatter.

Seed shatter refers to the release of mature seeds from the mother plant.

Each plant will release hundreds, sometimes thousands of seeds.

The individual seeds are tiny and brown, each less than a quarter of an inch long.

Garlic mustard seeds are light enough to be spread by wind.

They can also be dispersed by water or by contaminated soil movement.

However, seed dispersal is mainly by humans or wildlife carrying the seeds.

Seeds generally germinate within one or two years, but under optimal conditions can remain viable for up to five years.

There are many native members of the mustard family, such as cutleaf toothwort pictured here that also have cross shaped white flowers with four petals.

Garlic mustard can be distinguished from native mustards by their leaf shape.

Native species have compound leaves unlike garlic mustard, which has kidney or heart shaped simple leaves.

Garlic mustard spreads prolifically by seed and displaces native plant communities.

By using these key characteristics, you'll be able to properly identify this aggressive invader.

Identification is the first step in any invasive plant control program.