This farm escapee has become one of the commonest of the yellow crucifers (brassicas with cross-shaped yellow flowers) along roadsides and in waste ground in the Scottish Lowlands. Farmed for its high oil content, it also likes to spread into disturbed ground and meadows. About 36,000 hectares of rape are grown in Scotland each year so this spreading tendency is endemic. It is an annual or biennial plant, spreading through seed dispersal.
The flowers have the yellow cruciform shape with 4 petals as with many brassicas. 6 yellow stamens protrude from the middle of each flower, 4 long and 2 shorter, with richer yellow hook-shaped anthers. These cluster around a greenish-yellow style.
Leaves are mainly simple, that is undivided, but sometimes with shallow lobes, or shallow teeth, and narrow and pointed. Lobes are more pronounced near the bottom of the stem, while leaves take on a simpler shape further up the stem. The leaves grow alternately up the stem, one leaf per node. The stems are smooth and un-hairy, as are the leaves.
The fruit is a dry, cylindrical siliqua, ending in a long pointed ‘beak’ which contains no seeds. It splits open when ripe.
Rape, or Rapa, is also known as Swedish turnip, yellow turnip and oilseed rape.