SafePlants

Descurainia pinnata: Tansymustard

Descurainia pinnata, belonging to the mustard family (Brassicaceae or Cruciferae), is known by several common names, including western tansymustard, Menzies' tansymustard, Nelson's tansymustard, Payson's tansymustard, and simply tansymustard. It's also sometimes mistakenly called Flixweed.

Considerations for Pets

• The text notes that Descurainia pinnata has bitter-tasting leaves.
• One source mentions related pest control products.

Considerations for Children

• The plant has a reputation as a weed.

Taxonomy and Nomenclature

• Scientific Name: Descurainia pinnata (Walter) Britton
• Family: Brassicaceae (also known as Cruciferae)
• Synonyms: The text mentions Sisymbrium sophia as a synonym for Descurainia sophia and lists Descurainia incisa ssp. filipes as a synonym for Descurainia longipedicellata. The text mentions the name Sophia incisa as a synonym for Descurainia incana.
• Subspecies/Varieties: Descurainia pinnata var. brachycarpa is specifically mentioned.
• Etymology: The genus is named after François Descain (1658-1740), an 18th-century French botanist and physician/pharmacist.

Distribution and Habitat

• Descurainia pinnata is native to North America and has a broad distribution across the continent.
• It is rare in New England, restricted to calcareous cliffs in New Hampshire.
• It can be found in rocky, shrub-steppe habitats, such as in eastern Washington.
• It is also reported in central and western Kansas, central and western Canada and eastern Central Florida.
• Descurainia incana (Mountain Tansy Mustard) is described as found in semi-desert to subalpine regions, often in disturbed areas and meadows.

Ecological Role

• The plant can be considered a weed in some contexts.
• Studies have evaluated the effect of tansymustard residue on crops like corn.
• One source refers to "pest control products, articles and questions on Tansy Mustard," suggesting it might be considered a pest in certain situations.
• The text mentions it can be found in fields and rangelands.

Morphological Characteristics

• Descurainia pinnata is an annual or biennial cool-season forb, typically growing up to 2 feet tall.
• It is usually single-stemmed, leafy, and covered with fine, gray hairs.
• Leaves are alternate and the leaf margins are pinnately lobed or divided. Flixweed has leaves that are alternate, 2 to 3 times pinnately compound with very narrow or linear segments.
• The plant is showy when flowering but becomes ragged and inconspicuous as the seed matures.
• Stems are erect, simple or branched, pubescent to canescent with branched glandular and eglandular hairs.

Interactions with Other Organisms

• The Sara Orangetip butterfly (Anthocharis sara) has been observed on California Rock Cress (Arabis sparsiflora) in areas where Tansy Mustard (Descurainia pinnata) is also present.
• One photo shows a very small fly, possibly a leaf miner (Agromyzidae family), resting on a leaf of the plant.

Quirky Facts

• The name "Western Tansymustard" can be misleading, as the plant is found in areas not typically considered "western," such as eastern Central Florida.

Further Information

• Saint Mary's College of California.
• Discover Life.