garlic mustard

not listed

NNA - Not applicable

SNA - Not applicable

not listed

RN – Restricted noxious weed

Invasive

FACU - Facultative upland

FAC - Facultative

FACU - Facultative upland

Garlic mustard is an erect, 12″ to 40″ tall, biennial, herbaceous plant rising from a slender, white taproot that forms a shallow “S” just below the base of the stem. In the first year it produces a rosette of 3 or 4 leaves. The plants stay green over the first winter. In the second year it also produces one or two tall flowering stems. It forms dense stands that block virtually all sunlight from reaching the ground. Second-year plants die by late June, leaving only the erect stalks with dry, pale brown seedpods. All parts of the plant smell like garlic.

The stems are usually unbranched, sometimes slightly branched. They are hairless of have a few simple hairs.

The first year leaves are kidney-shaped, about 2″ wide and 2″ long. They are green, hairless, coarsely toothed, and deeply veined. They are on leaf stalks that are about as long as the leaf.

The second year leaves are similar to those of the first year. The basal leaves are kidney-shaped. The stem leaves are alternate, light green or yellowish green, with pointed tips, heart-shaped near the bottom of the stem, becoming smaller, more triangular, and nearly stemless as they ascend the stem.

The inflorescence is a short, button-like cluster at the end of each stem.

The flowers are small, ⅓″ wide, with 4 white petals The petals have rounded tips and narrow to the base.

The fruits are slender, 4-angled, 1″ to 2½″ long pods containing single rows of seeds. The pods spread widely, from horizontal to erect. they becomes shiny black when mature.

12″ to 40″

White

The coarsely toothed triangular stem leaves and kidney-shaped basal leaves that smell of garlic when crushed make this plant easy to identify.

Mints have similar leaves but their leaves are always opposite and their stems are conspicuously 4-angled.

Bitter cresses (Cardamine spp.) are similar but their leaves are never coarsely toothed, and the flowers are on longer flower stalks.

Moist to moderate moisture. Woodlands, wood edges, trail edges, roadsides. Partial or full shade.

April to June

Garlic mustard produces chemicals that help it compete against nearby plants (allelopathy). The roots and leaves exude toxic chemicals that suppress mycorrhizal fungi that other plants need to absorb nutrients from the soil. The mycorrhizal fungi that garlic mustard needs is not suppressed. The chemicals also inhibit the growth and germination of competing plants.

Garlic mustard also produces chemicals to defend against herbivores. All parts of the plant exude a strong garlic odor. Deer avoid garlic mustard and eat neighboring plants, helping garlic mustard increase its population. It is also toxic to some insects, including the mustard white butterfly.

Garlic mustard seeds remain viable in the soil for up to five years.

Sources

2, 3, 4, 7, 22, 28, 30.

Native to southern and eastern Europe, Northern Africa, Asia, and the Indian subcontinent. Introduced into the North America as a potherb. Escaped cultivation and naturalized.

Common

Habitat

Plant

Inflorescence

Flowers

Leaves

Leaf

Infructescence