Medium to tall, bristly plant, lower leaves, large and lyre shaped, upper are lanceolate, not clasping the stem. Flowers yellow, 15 to 20 mm. Fruit 25 to 45 mm long and beaded, sometimes bristly.

Oil-seed Rape and White Mustard (Sinapis alba)

Leaves either un-lobed or with large terminal lobe.  Can be hairy or glabrous. Sepals patent (i.e standing out at right-angles).  Fruits long, with a distinct beak.

White mustard is similar - deeply pinnately lobed leaves, and fruits are usually bristly-hairy

General photo of plant in habitat, and details of flowers and fruits

Arable fields, waste and disturbed ground, roadsides.

April to October.

Annual.

Common throughout much of Britain.

Common in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 518 of the 617 tetrads.

In the current Checklist (Jeeves, 2011) it is listed as Alien (archaeophyte); occasional.