Tansy Mustard

Descurainia pinnata



Tansy mustard is an annual cool- season forb growing to 2 feet tall. It is usually single stemmed, leafy and covered with fine, gray hairs.

Leaves are placed alternately along wavy stems, with each divided into many small segments.

Flowers vary from yellow to whitish, occurring in long clusters at stem ends. Plants flower in February through May.


Tansy mustard is distributed widely throughout the southern and western United states up to 7000 feet in elevation. Heavy stands may form on dry, sandy soils in arid areas. Abundance increases after moderate or heavy winter rains in the arid southwest.

Toxic Agent

The toxic agent is unknown. Large quantities of the plant must be consumed before poisoning occurs. Tansy mustard also accumulates toxic levels of nitrate.

Signs of Livestock Ingestion

Cattle are the only kind of livestock reported to be poisoned. The first clinical sign is partial or complete blindness (blind staggers). Animals wander aimlessly until exhausted, or may stand pushing their head against a solid object for hours.

next, or along with the blindness, comes an inability to use the tongue or to swallow (paralyzed tongue). Cattle may stand at water unable to drink, or try unsuccessfully to graze.