Alliaria petiolata (Bieb.) Cavara & Grande

Garlic Mustard

Alliaria petiolata plant

Family - Brassicaceae

Habit - Biennial forb.

Stems - To +1m tall, herbaceous, single or multiple from thick taproot (with a radishlike aroma when crushed or bruised), erect, branching above, pubescent at very base, glabrous and glaucous above.

Alliaria petiolata stemUpper stem.

Alliaria petiolata stemLower stem.

Leaves - Alternate, glabrous above, sparsely pubescent below. Basal leaves reniform, crenate or sinuate, petiolate, to 10 cm broad, 8 cm long. Petiole to 15 cm long, with single longitudinal groove, groove ciliate on margins. Cauline leaves gradually reduced upwards, cordate to sagittate, sinuate to coarsely toothed.

Alliaria petiolata leafLower cauline leaf.

Alliaria petiolata leafUpper cauline leaf.

Inflorescences - Terminal racemes, greatly elongating in fruit.

Alliaria petiolata inflorescence2Inflorescence.

Flowers - Petals 4, white, glabrous, clawed (the claw to 2 mm long), 6-7 mm long, 3 mm broad at apex. Stamens 6. Filaments to 3 mm long, glabrous, white. Anthers yellow, 1 mm long. Ovary green, 4-angled, 3 mm long, glabrous. Style very short. Sepals 4, whitish with light green tips, 3-4 mm long, 1-2 mm broad, linear to subulate. Pedicels to 4 mm long, glabrous.

Alliaria petiolata flowerFlower.

Fruits - To 5 cm long, 4-angled, glabrous, on thick stalk to 6 mm long, erect and parallel to stem, many seeded, style persistent as a short beak. Fruit stalks at right angles to stem.

Flowering - April - May.

Habitat - Low woods, slopes, streambanks, roadsides, railroads.

Origin - Native to Europe.

Other info. - This plant is infamous as a noxious invasive of moist, shaded areas. It is particularly troublesome in northern areas of the U.S., but rare or absent in much of the southern U.S., and probably less of a problem in Missouri than in the northern regions. Once established, it is difficult to eradicate, having self-compatible flowers and seeds which remain viable in the soil bank for many years. Conventional wisdom asserts that seeds will continue to mature on plants which have been uprooted at an immature stage; thus collected plant material should be burned or removed from the area.

The plant was a deliberate introduction to North America, having a long European tradition of use as a potherb, salad green, garlic substitute, and source of seed oil. The leaves are edible, with a flavor reminiscent of garlic and radish. It has also been used medicinally. The flowers are fairly showy and the plant is visually attractive but it should not be spread.

Photographs taken at Eagle Bluffs Conservation Area, Boone County, MO., 4-11-04 (DETenaglia); also near St. Albans, Franklin County, MO, 4-6-2010 (SRTurner).