Descurainia pinnata is a species of flowering plant in the mustard family known by the common name western tansymustard. It is native to North America, where it is widespread and found in varied habitats. It is especially successful in deserts. It is a hardy plant which easily becomes weedy, and can spring up in disturbed, barren sites with bad soil. This is a hairy, heavily branched, mustardlike annual which is quite variable in appearance. There are several subspecies which vary from each other and individuals within a subspecies may look different depending on the climate they endure. This may be a clumping thicket or a tall, erect mustard. It generally does not exceed 70 centimeters in height. It has highly lobed or divided leaves with pointed, toothed lobes or leaflets. At the tips of