Field Penny-cress – Thlaspi Arvense: Edible & Medicinal Uses of the Jet Fuel of Wild Plants

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Field penny-cress is a slightly edible and medicinal plant may have a future in renewable fuels.

Field penny-cress (Thlaspi arvense) is listed as uncommon in Haliburton Flora. It is sometimes found along roadsides or on old farmland mixed in with tall grasses. It prefers disturbed areas, so even though it’s not native here it’s not aggressively spreading into the wild. A related and similarly used plant, garlic pennycress (Mummenhoffia alliacea) is much more aggressive. It is just starting to spread here and may be covered on its own in the future.

The eye-catching large coin-shaped seedpods (at least 1/3″ long when mature) are unique in the mustard family, which generally has long skinny seedpods. It makes pennycress hard to mistake when going to seed:

Edible Uses of Field Penny-cress

The bitter, tender young leaves can be eaten raw or cooked as a potherb. They have a distinct garlicky mustard flavour. The bitterness can be parboiled out in 1-2 changes of water.

The empty seed pods have a peppery flavour and can be used as a mustard powder substitute, but the seeds themselves are the subject of some debate. They are so high in erucic acid, some sources do not recommended the seeds for human consumption, at least regarding in high amounts and/or for younger growing humans. Farmers and pet owners beware – there is no debate that the plant is poisonous to animals.

Medicinal Uses of Field Penny-cress

Field Penny-cress is primarily said to support these body systems:

  • Integumentary

Medicinal tags include Antibacterial, Antimicrobial, Astringent, Diuretic, and Stimulant. See Medicinal tag key for more information.

Common usage includes as an antimicrobial wash for abscesses and certain other skin conditions.

The high mustard oil content of this mustard relation can irritate skin. It’s also photosensitive.

Alternative Uses of Stinkweed

That high erucic acid content that makes the seeds perhaps toxic to some degree also makes the oil suitable for jet fuel and biodiesel production. We’ll have to wait and see if it really has a future in renewable fuels.

Growing Thlaspi Arvense

You know those little white butterflies? Cabbage white (specifically pieris rapae), like pennycress, is an introduced species here. I’m used to hearing that about plants, but I was surprised when I first heard these common white butterflies were also introduced. Its caterpillars feed on cabbage relations including pennycress. As a nonnative, this plant has few insect allies of note, but will attract some small bees and flies, and also the caterpillars of the purple-backed cabbageworm moth (evergestis pallidata).


And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess.

2) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

3) For medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

4) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

5) Many plants have look-a-likes, and sometimes they are poisonous.

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