Field mustard

General distribution:

Field mustard is an upright winter annual or biennial that is a member of the mustard family (Brassicaceae). The oil made from the seed is sometimes also called canola or colza, which is one reason why it is sometimes confused with rapeseed oil.

This species is native to Eurasia, but has spread all over the world and is now naturalized throughout much of North America. 

Map of distribution and habitat in Canada

This plant is present in at least 63 states/provinces in this country.

See The Map

Botanical description:

Plants exist as basal rosettes until flowering stems develop at maturity, usually in the second year. Plants grow 1 to 3 (or 4) ft tall from a sometimes fleshy, enlarged taproot, with a many-branched stem. The foliage is generally hairless and sometimes covered with a whitish film. Lower leaves can reach 12 inches long, have a large central lobe, and usually one to four pairs of smaller side lobes. Upper leaves are smaller, non-lobed, and have a pointed tip and widened, clasping base. The bright yellow flowers are clustered at stem tops and have four petals that are 1/4 to 1/2 inch long.

Seasonal development:

Plants flower from June to August, depending on climate and latitude, and are insect-pollinated and self-incompatible.