kcweeds

Garlic Mustard Look-a-like Guide

Identification
Look-a-likes
If you find it

BREAKING LOCAL NEWS: nearly 30 years after being introduced the Seattle area, to the King County Noxious Weed Program’s dismay, garlic mustard (a legally regulated Class A Noxious Weed) has finally been found on Vashon Island. Garlic mustard is required for eradication statewide here in Washington state, in King County our Program is here to offer land managers technical and physical support for regulated weeds like this one. If you think you have garlic mustard or another regulated weed on property you tend to, email us with a clear photo and the nearest address at noxious.weeds@kingcounty.gov.

The good news is – we can prevent garlic mustard from being a bigger problem by keeping an eye out for this plant in our areas. The key to effective support here will be successful plant ID. Garlic mustard has A LOT of local look-a-like plants, so let’s get into it. 

Garlic mustard is written into Washington state law.

First, you might be asking yourself: what is garlic mustard and why does it matter? That could be an entire post of its own. In brief, garlic mustard is an invasive introduced plant that thrives in healthy forest understories and outcompetes native species through early season growth, high seed production, and chemical interference with soil fungi, ultimately disrupting forest ecosystems and proving difficult to control. Control is legally required for this plant in the state of Washington as an effort to prevent it from being a larger issue; King County has been managing all new and known infestations since 1998.  

Learn more about it here on our garlic mustard webpage. 

Unlike most other weeds that show up most in disturbed/developed areas, garlic mustard can thrive in otherwise healthy forest understories. Every infestation started with a single plant!

Garlic Mustard Identification Tips

Key features:

  • Smell: crushed leaves/roots smell like garlic
  • Leaves: Not noticeably hairy, 2-4 inches wide. Shape changes up the upright stem. 1st year plants only have basal leaves.
    • Basal leaves: kidney shaped/wavy scalloped edges; upper leaves: triangular/pointy scalloped edges. 
  • Stem: round upright stems have sparse soft white hairs but may look hairless from a distance. 
  • Height/habit: 1st year: low growing rosette; 2nd year: 1-3 ft tall – leaves grow alternate along stem. 
  • Flowers: tiny, white, 4 petals (spring bloom); grow in clusters at the tips of branches. 
  • Seed Pods: Thin, upright banana-like pods. Start green, turn yellow to brown over time.
  • Habitat: Typically forms dense patches in shady areas but can thrive in most any setting. 
At established sites, you can expect to find 2 generations of garlic mustard plants. 1st year plants will be growing lower to the ground, whereas 2nd year plants will have an upright stalk. Prioritize controlling 2nd year plants as they will make seeds first.
1st year plants grow in rosettes (circular arrangements of low growing leaves) and have kidney shaped leaves. 2nd year plants grow upright; leaves change along the stem – rounder towards the base and becoming more triangular/narrow towards the top.
Not pictured: smell! Crushed leaves and roots have a garlicy odor. Smell strength varies based on growing conditions and where it is in its lifecycle.

Garlic Mustard Look-a-likes

Check out our 2-page field guide to garlic mustard look-a-likes! Keep reading to dive into more detail about each species. 

Garlic-Mustard-Look-a-likes_guideDownload

Species

This list is non-exhaustive and includes those that we most often get false reports of as garlic mustard.

Money Plant (Honesty)
Nipplewort
Ground-ivy & mints
Violets
Mallows
Fringe Cups
Large-Leaf Avens
Piggyback Plant
Stinging Nettle

To learn more about any of the plants below, click on its name (brings you to its iNaturalist species webpage).

Money Plant / Annual Honesty (Lunaria annua)

Introduced species

  • Similar leaf shapes to GM, but toothed edges come to fine points under a close eye
  • Fuzzy leaf (versus GM which at most has sparse hairs)
  • Found in similar environments
  • Large bright purple flowers, similar bloom time
Comparison of garlic mustard and money plant leaves, highlighting differences in texture and edge shape.
Money plant and garlic mustard have similar growth times and look very similar in their 1st year, as pictured above.
A garden scene displaying two plants: Garlic Mustard (Alliaria petiolata) on the right, featuring its green leaves and flower buds, and Money Plant or Annual Honesty (Lunaria annua) on the left, showcasing purple flowers with some white blooms in close-up. Labels identify each plant.
Leaf sizes vary on both species depending on growing conditions. The leaf shape is more important than size. Flowers are helpful too, but not helpful unless plants are in bloom.

Nipplewort (Lapsana communis)

Introduced species

  • Extra lobes develop towards base of each leaf
  • Mature plants have narrow/lance-like leaves towards the top
  • Small yellow dandelion-like ray flowers grow at branching tips later in the season
  • Seed vessels are tiny white fluff balls
Side-by-side comparison of Nippletwort and Garlic Mustard plants, showcasing their basal and upper leaves.
1st year plants are similar in size. Nipplewort leaf lobes are helpful species indicators but may not be present until the plant is more developed, so it’s helpful to check for other factors like smell and stem hair.
Side-by-side comparison of Nipplewort and Garlic Mustard plants, highlighting distinguishing features including their flowers and leaves.
2nd year plants look most similar before flowers develop.

Ground-ivy (Glechoma hederacea) and other mints

Introduced species

  • Similar leaf shape, but much smaller in size
  • Plants grow lower to the ground, “crawling” habit
  • Other mints are often confused, but plants in the mint family have features that distinguish them from GM including:
    • Square/fuzzy or hairy stems
    • “opposite” leaf arrangement
A comparison image showing Ground-ivy and Garlic Mustard. Ground-ivy leaves are smaller (½ to 1 inch) and have a boxy stem with an opposite leaf arrangement, while Garlic Mustard leaves are larger (2 to 4 inches) and have a distinct shape. Both plants are shown with identifying features highlighted.
Other mint family plants can cause confusion due to similar growth habits and leaves. Look for a square stem, opposite leaves, and a minty smell when leaves are crushed to verify the plant is not garlic mustard.

Violets (Viola spp.)

Group (genus) that includes native & introduced species

  • Similar leaf shape to GM basal leaves, but sizes vary
  • Leaves may be rougher in texter and more jagged along the edges
  • Grow much lower to the ground, does not develop tall upright stems
  • Flowers vary in color but have unique structure of 5-petals with the bottom petal being more forward growing and distinct
Image showing garlic mustard (Alliaria petiolata) surrounded by smooth yellow violet (Viola glabella) flowers. The leaves of garlic mustard are highlighted with an arrow, while both plant species are depicted for identification purposes.
Violets have a lot of variation and are most often confused with garlic mustard when flowers are not present-pay close attention to leaf margins. Crush leaves or roots to check for a garlicy smell that indicates garlic mustard, it may be subtle!

Mallows (Malva spp.)

Group (genus) that includes native & introduced species

  • Rounded to palmate leaf shape with unique folds/pleats
  • Leaf edges may be gently toothed, rough or fuzzy texture
  • Leaf/plant size varies between species, may grow crawling or upright
  • Flowers have 5 notched (heart-shaped) petals, often with stripes
Comparison of leaves from common mallow, dwarf mallow, and garlic mustard showcasing their distinct shapes and textures.
Mallows are most often confused in their early growth stages. Leaves are key!

Fringe cups (Tellima grandiflora)

Native species

  • Overall a more fuzzy/hairy plant (leaves and stems)
  • Round to heart-shaped leaves with shallow lobes (palmate), toothed edges
  • Tall stalks of tiny fringed greenish white (sometimes pink) cup flowers when mature
  • Leaves can have reddish/purplish hue in certain conditions
Close-up of two plants: Fringe Cups (Tellima grandiflora) and Garlic Mustard (Alliaria petiolata), showcasing the distinct leaf shapes and textures.
Fringe cups can resemble garlic mustard at most stages, but its leaves are more pointed/sharply toothed and stem is much hairier.
A close-up comparison of Fringe Cups (Tellima grandiflora) and Garlic Mustard (Alliaria petiolata) in a natural setting, showcasing their distinct flower and leaf structures.
Fringe cup flowers grow on stalks; garlic mustards grow in singular clusters.
A close-up view of two plants: Fringe Cups (Tellima grandiflora) with bright green, lobed leaves and tall flowering stalks on the left, and Garlic Mustard (Alliaria petiolata) with scalloped leaves and white flower clusters on the right, set against a backdrop of trailing ivy.
These plants often grow in similar environments, but as we control garlic mustard we make room for native species like this one to thrive!

Large-Leaf Avens (Geum macrophyllum)

Native species

  • Compound basal leaves – each leaf has stacked leaflets that start in small pairs at leaf base and get larger towards tip, ending with significantly larger terminal leaf
  • Uppermost leaves on upright stems have 3 large/sharp lobes
  • Yellow flowers with 5-petals and a bristly center
  • Fuzzy/hairy stems
Comparison of Large-Leaf Avens and Garlic Mustard plants, highlighting their young and mature leaves.
A keen eye can tell the difference between avens and garlic mustard without an issue, but we’ve gotten enough reports of it that we had to include it to be safe! Leaf shape is key.

Piggyback plant (Tolmiea diplomenziesii)

Native species

  • Fuzzy leaves, mature leaves will form “plantlets”: a smaller leaf or set of leaves at its base that can fall off and form new plants
  • Low growing basal leaves with tall stalks of small tubular purplish/brown flowers
Comparison of Piggyback Plant (Tolmiea menziesii) and Garlic Mustard (Alliaria petiolata) with labeled features.
Piggyback plants are most often confused when young, but their toothed edges come to sharp tips.

Stinging nettle (Urtica gracilis)

Native species

  • This plant physically stings you when touched. Garlic mustard does not do this! 
  • Leaf margins are more sharply toothed
  • Stems and parts of leaves have sharp hairs
  • Stems are square, leaves are “opposite”
  • Flower clusters on mature plants look like hanging droops of grain
Top left: Stinging Nettle (Urtica gracilis) showing its serrated leaves and hairy stems. Top right: Garlic Mustard (Alliaria petiolata) with small white flowers and upright stems. Bottom left: Young Stinging Nettle plants showcasing their jagged leaves. Bottom right: Garlic Mustard seedlings featuring large, rounded leaves.
If the plant stings when you touch it, it’s not garlic mustard!

What to do if you find it

In King County, Washington

Please notify us if you see garlic mustard growing in King County. Email us with clear photo(s) and the nearest address: noxious.weeds@kingcounty.gov

Property owners are legally required to control garlic mustard plants on their property. We can provide the property owner or public agency with site-specific advice on how best to remove it. Also, because garlic mustard is not established everywhere in King County, we can stop it from spreading if we act quickly. We map all known locations of regulated noxious weeds to help locate new infestations in time to control them.

Another county in Washington state

Garlic mustard is required for control statewide. Contact your local county noxious weed board to identify your next steps in your area. We recommend sending clear photo(s) and the nearest address. Find your county weed board here: Washington State Noxious Weed Control Board

Somewhere else

Find out if garlic mustard is a problem in your area. Tip: search “[your state] noxious weeds” or “garlic mustard [your state]” to see what has been done locally. Many state universities have “extension” programs that address issues like noxious weeds, or groups of certified “Master Gardeners” that may prove helpful.

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