The oilseeds known as canola are sometimes particular varieties of `` Brassica rapa '' ( termed Polish Canola ) but usually the related species `` Brassica napus '' ( rapeseed ) and `` Brassica juncea '' ( mustard greens ) .
The oilseeds known as canola are sometimes particular varieties of `` Brassica rapa '' ( termed Polish Canola ) but mostly the related species `` Brassica napus '' and `` Brassica juncea '' .