Garlic Mustard (Alliaria petiolata)

Garlic Mustard Weed - Herbaceous biennial with stems 1–4’ tall as flowering plant. First year plants form a basal rosette that remains green through the winter. Second-year plants produce one to several flowering stems.

Herbaceous biennial with stems 1–4’ tall as flowering plant. First year plants form a basal rosette that remains green through the winter. Second-year plants produce one to several flowering stems.

Legal classification in WI: Restricted

Leaves: First year plants are 2–4” tall rosettes with 3–4 heart-shaped leaves, with a toothed margin. Second year plants produce a flowering stalk with 2–3” wide alternate, triangular leaves. Foliage emits a distinct onion or garlic smell when crushed.

Flowers: Late spring to early summer of second year, producing numerous small, white, fourpetaled flowers.

Fruits and seeds: Fruits are slender capsules (siliques) 1–2.5” long and contain a single row of oblong black seeds with a distinct ridge.

Roots: Taproot that often has a distinctive S-shaped curve near the top of the root.

Similar species: Creeping charlie (Glechoma hederacea) is often confused with garlic mustard, but its prostrate growth with stolons allows for differentiation from garlic mustard.

Ecological threat:
• Invades upland forests, floodplain forests, savannas, yards, and roadsides. It is typically found in shaded areas, but can be found in full sun. Cannot tolerate acidic soils. Invasion of forests usually begins along the wood’s edge, and progresses via streams and disturbed areas.
• Exudes antifungal chemicals into the soil that disrupt associations between mycorrhizal fungi and native plants, suppressing native plant growth.

For more information visit: http://ipaw.org/invaders/garlic_mustard/index.aspx

Photo released under creative commons license.

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