Page author: David Giblin
Thlaspi arvense
fanweed, field pennycress

Distribution: Distributed widely throughout Washington; widely introduced throughout North America.

Habitat: Weed of waste ground, low to moderate elevations.

Flowers: April-August

Origin: Introduced from Europe

Conservation Status: Not of concern


Glabrous annual, the stem simple to freely-branched, 1-5 dm. tall.


Basal leaves few, 2-6 cm. long, scalloped to almost lyrate, narrowed to a short petiole; lower cauline leaves similar to the basal, but gradually changing upward, ultimately sessile, auriculate, lanceolate to oblanceolate, and dentate to wavy-lobed.


Inflorescence a large, terminal, bractless raceme; pedicles slender, spreading to up-curved, 7-15 mm. long; sepals 4, erect,1.5-2.2 mm. long; petals 4, white, 3-4 mm. long; stamens 6; style nearly lacking.


Silicles strongly obcompressed, oval to oblong-obcordate, narrowly notched, 10-17 mm. long, wing-margined all around, the sinus 1.5-2.5 mm. deep; seeds in 1 series.

Accepted Name:
Thlaspi arvense L.
Publication: Sp. Pl. 2: 646. 1753. 1753.

Synonyms & Misapplications:
Teruncius arvensis (L.) Lunell
Additional Resources:

PNW Herbaria: Specimen records of Thlaspi arvense in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Thlaspi arvense checklist entry.

E-Flora BC: Thlaspi arvense atlas page.

CalPhotos: Thlaspi arvense photos.

USDA Plants: Thlaspi arvense information.

23 photographs:
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