Field Pennycress
Thlaspi arvense
Other names: Stinkweed
Family: Brassicaceae, Mustard
Genus: Thlaspi

Plant height: 10-50 cm tall.
Growth habit:
erect annual.
Stems: simple to freely branched, leafy, hairless.
Leaves: mostly alternate, oblanceolate, 2-6 cm long,
the lower strongly wavy-margined to almost lobed, with
larger end lobe, narrowed to a short stalk. Leaves farther
up becoming stalkless, with ear-shaped lobes at base.
Basal leaves few, withering by flowering time.
Flowers: white, in open clusters on branches, with
4 petals 3-4 mm long and sepals 1.5-2.2 mm long.
Flowering time: May-August.
Fruits: pods strongly flattened, oval or heart-shaped,
shallowly notched, 10-17 mm long, with winged edge all
around, the notch 1.5-2.5 mm deep. Stalks slender,
spreading to upcurved, 7-15 mm long. Style almost
lacking, 0.1-0.2 mm long. Seeds about 2 mm long, not
edged, wrinkled lengthwise.

Common weed on disturbed ground in all parts of MT.
Introduced from Europe, now spread across N. America.

Edible, Toxic and Medicinal.
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Edible uses:
Young leaves of field pennycress were used for food by the Cherokee Indians.
Even the young leaves have a somewhat bitter flavor and aroma, and has been added in small quantities to salads and other foods. However, this plant is not recommended to use for food because its toxic properties, see below.

The plant contains sufficient quantities of glucosinolates to be toxic. During dry periods, cattle in western Canada have ingested hay containing high quantities of stinkweed, or field pennycress. Poisoning, death and abortion occurred. Tests of field pennycress showed that the allylthiocyanate (a glucosinolate) content is sufficient to cause sickness and death in cattle. Fatalities occurred at about 65 mg/kg of body weight. The amount of this chemical varies with the stage of maturity of the plant, the highest amount is in the seeds. Cattle that ingested hay containing between 25-100% field pennycress were colicky and some abortions occurred. Ensiling hay containing field pennycress apparently prevented liberation of allylthiocyanate.

Medicinal uses:
The entire plant is anti-inflammatory and acts as a blood tonic and blood purifier. It has agents that induces sweating, agents that induces the removal (coughing up) of mucous secretions from the lungs. It is fever-reducing and promotes the well-being of the liver and increases the secretion of bile. The seed is a tonic. Both the seed and the young shoots are said to be good for the eyes. The seeds are used in Tibetan medicine and are considered to have an acrid taste and a cooling potency. They are anti-inflammatory and fever-reducing, and are used in the treatment of pus in the lungs, renal inflammation, appendicitis, seminal and vaginal discharges. Field pennycress was used medicinally by the Iroquois Indians. They made an infusion of the plant taken for sore throats.
Pennycress also has a broad antibacterial activity, effective against the growth of staphylococci and streptococci.

Other uses:
Seed of field pennycress might be useful for making biodiesel (it is 36 to 40 percent oil by weight) and a nature-based weed killer. The seed oil can be used for lighting.

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