Tansy Mustard

Biological Name:

Descurainia pinnata (Tansy-Mustard)

Natural Habitat:

Tansy-Mustard: Typically found in dry, rocky habitats in western North America.


Tansy-Mustard also known as Descurainia is a plant that is native to grassland and prairie regions of North America. It is an annual herb that can grow up to two feet tall and it has small oval-shaped leaves and small yellow or white flowers that bloom in the spring. The plant is known for its tansy-like aroma and it is often found in disturbed or degraded habitats.

Frequently Asked Questions (FAQs)

Q: What is tansy mustard used for?
A: The seeds are edible raw or cooked and have been used as piñole. The seeds can also be used to flavor soups, as a condiment ground into a powder mixed with cornmeal, used to make bread or to thicken soups and stews. In Mexico the seeds are made into a drink with lime juice, claret and sweet syrup.

Q: What are the benefits of tansy?
A: Tansy is also used to treat roundworm and threadworm infections in children. Other uses include treatment of epileptic seizures, colds, fever, hysteria, gout, kidney problems, and tuberculosis. It is also used to kill lice and bacteria; promote sweating; calm the nerves; and act as an antioxidant, tonic, and stimulant.

Q: Why did people drink tansy oil?
A: Tansy is used for digestive tract problems including stomach and intestinal ulcers, certain gallbladder conditions, migraines, nerve pain, joint pain, and many other conditions, but there is no good scientific evidence to support these uses.

Q: What does tansy mustard look like?
A: Flowers are up to 1/8 inch across with 4 spreading to ascending, spoon-shaped, yellow petals alternating with 4 egg-shaped yellow sepals that are slightly shorter than the petals. In the center is a stout style surrounded by 6 yellow stamens about as long as the petals.

Q: Is tansy mustard toxic?
A: Poisoning in humans is not uncommon. Tansy mustard (Descurainia pinnata) is an annual weed that grows on dry, sandy soils in arid areas. Intoxication occurs primarily in cattle only after large amounts of this plant have been eaten over extended periods of time.

Q: Is tansy mustard toxic to dogs?
A: Harmful content: Even though tansy is used as a natural insect repellent and sometimes as a culinary herb or alcohol flavoring, the thujone content of common tansy makes the leaves and flowers particularly toxic to dogs.

Q: Can you eat tansy mustard?
A: The plant produces alkaloids (neurotoxins and cardiotoxins) that are toxic to humans and livestock if consumed in large quantities. Common tansy has been used for medicinal purposes; human consumption has been practiced for centuries with few ill effects, but the toxic properties of the plants are cumulative.

Q: How toxic is tansy?
A: Jacobaea vulgaris, Asteraceae Family Tansy ragwort (Jacobaea vulgaris), a regulated Class B noxious weed, is a toxic biennial found throughout King County, especially on open, sunny sites such as in pastures and on roadsides. Eating it can sicken or even kill cattle, horses, some goats, pets, and people.

Q: What kills tansy mustard?
A: Applications with products with active ingredients like 2, 4-D, dicamba, triclopyr, and glyphosate have been reported to control mustard weeds. If organic options like acids or oils are preferred, make sure that the product that you use is labeled as a herbicide, such as enhanced vinegars.

Q: What insects does tansy repel?
A: Tansy is also a staunch garden protector. There are impressive claims that it repels all kinds of pests such as ants, flies, fleas, moths, mosquitoes, ticks, and even mice.

Q: Where does tansy mustard grow?
A: Fine-leaved tansy-mustard is a Eurasian species introduced in much of the rest of the world, including most of North America. In New England it is common in farm yards, fields, roadsides, railways and other disturbed areas.

Q: How poisonous is tansy?
A: It is toxic to all classes of livestock but most toxic to cattle and horses. At doses likely to be ingested, it causes a chronic liver disease that is seen as a cirrhosis-like hepatic degeneration.

Q: Can cows eat tansy mustard?
A: Tansy mustard (Descurainia pinnata) is an annual weed that grows on dry, sandy soils in arid areas. Intoxication occurs primarily in cattle only after large amounts of this plant have been eaten over extended periods of time.

About the author

Samuel is a gardening professional and enthusiast who has spent over 20 years advising homeowners and farm owners on weed identification, prevention and removal. He has an undergraduate degree in plant and soil science from Michigan State University.