Alliaria petiolata (Garlic mustard)

Alliaria petiolata (M. Bieb.) Cavara & Grande

Garlic mustard

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Rosidae	Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more
Order	Brassicales	Mustard, cabbage, caper, papaya, nasturtiums, many others; most produce mustard oil
Family	Brassicaceae	Mustards, cabbages
Genus	Alliaria	Derived from Latin allium, “onion” or “garlic”
Species	petiolata	“Stalked”

About plant names...

Garlic mustard is native to Europe, Asia, northwestern Africa, and parts of India and China. “Garlic mustard” is so-called because the crushed leaves smell faintly of garlic, and the leaves, flowers and fruits taste like mild garlic and mustard. (The plant is a member of the mustard family.) Originally introduced to North America during the 1800s as a culinary herb, it is now naturalized and widespread. It has found itself a place on the Plant Conservation Alliance’s Alien Plant Working Group Least Wanted list, and on many similar lists. In addition to replacing large areas previously populated by a variety of wildflowers, garlic mustard inhibits ectomycorrhizal fungi, which play a key role in forest ecosystems.

Identification: Plants are 12-51" (30-130 cm) tall. Young leaves are triangular, with fairly sharp-toothed serrations; older leaves are heart-shaped, with rounded serrations; all are wrinkly. Leaves are 1¾-3" (5-7.5 cm) long and ¾-2" (2-6 cm) wide. Groups of small white flowers, each less than ¼" (6.3 mm) in diameter, with four petals, appear on the top. The fruits, called siliques, resemble tiny upward-pointing bean pods.

Plants that are often found near garlic mustard include Cut-leaved toothwort, sweet cicely, and early saxifrage. All three of these are occasionally confused with garlic mustard. However, the leaves differ greatly in these species. Cut-leaved toothwort has very narrow, dark green leaves. Sweet cicely has deeply divided, fernlike leaves and 5-petaled white flowers on stalks. Early saxifrage has leaves only at the base, and branching groups of tiny white flowers on long stalks. Its leaves are vaguely similar, but oval-shaped, not heart-shaped.

Garlic mustard spreads quickly, replacing local plants, because it employs a trick the locals aren’t prepared to defend against. Native plants work in synergy with a soil fungus to extract nutrients from the soil. Garlic mustard releases sinigrin. This turns into mustard oil, the same stuff that gives mustard and horseradish its kick. But it also kills the beneficial fungi. (And here you thought mustard evolved to go on top of hot dogs, not wage war against other plants!) But native plants eventually learn to fight back. For example, clearweed plants (Pilea pumila) found near garlic mustard have developed improved resistance to sinigrin. See the Science News article Native Species Fight Back: First Evidence of Coevolution Between Invasive, Native Species for details.

Edibility: Leaves, flowers and fruit taste mildly of both garlic and mustard, and can be used to flavor salads and pesto.

Online References:

Alliaria petiolata on Missouriplants.com

Alliaria petiolata on Wikipedia

Alliaria petiolata on Invasive.org, Center for Invasive Species and Ecosystem Health

Alliaria petiolata on the USDA Forest Service's Fire Effects Information Database

Alliaria petiolata at Illinois Wildflowers

Alliaria petiolata on Plants for a Future, a resource and information centre for edible and otherwise useful plants

Alliaria petiolata on Kansas Wildflowers and Grasses

Alliaria petiolata on the Plant Conservation Alliance’s Alien Plant Working Group Least Wanted List

4/30/2010 · Nashua River Rail Trail, Ayer, Massachusetts
≈ 3 × 2½" (7.8 × 6.6 cm)

5/7/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 10 × 15" (26 × 39 cm)

5/6/2016 · Nashua River Rail Trail, Groton, Groton, Massachusetts

4/4/2012 · North Central Railroad Trail, End, Phoenix, Maryland
≈ 5 × 3½" (13 × 9.4 cm)

10/16/2016 · Appalachian Trail, Mount Everett, Mt. Washington, Massachusetts
≈ 8 × 5" (20 × 13 cm)

Alliaria alliaria (L.) Britton

Alliaria officinalis Andrz. ex M. Bieb.

Erysimum alliaria L.

Sisymbrium alliaria (L.) Scop.

Alliaria alliaria (L.) Britton

Alliaria alliaria (L.) Britton nom. inval.

Alliaria petiolata description by Thomas H. Kent, last updated 5 Oct 2021.

5/6/2016 · Nashua River Rail Trail, Groton, Groton, Massachusetts

4/27/2010 · Nashua River Rail Trail, Pepperell, Massachusetts
≈ 6 × 4" (16 × 10 cm)

6/7/2010 · Nashua River Rail Trail, Pepperell, Massachusetts
≈ 11 × 15" (26 × 37 cm)

10/16/2016 · Appalachian Trail, Mount Everett, Mt. Washington, Massachusetts
≈ 7 × 4½" (18 × 12 cm)

5/6/2016 · Nashua River Rail Trail, Groton, Groton, Massachusetts

5/4/2017 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 4½ × 7" (12 × 18 cm)

4/29/2010 · Bruce Freeman Rail Trail, Chelmsford, Massachusetts
≈ 14 × 14" (36 × 34 cm)

Range:

About this map...