Swedish turnip ( Brassica napus ) in the mustard family .
A hardy biennial, the rutabaga is a cool-season plant cultivated for its fleshy roots and tender leaves. Related to the turnip, it requires a longer growing season but is more tolerant of cold; in addition, its flesh is firmer and more nutritious and its roots keep much better during winter. White-fleshed varieties have a rough, green skin and bright canary-coloured flowers. Yellow-fleshed varieties have a smooth green, purple, or bronze skin and buff-yellow or pale orange flowers. Rutabagas are extensively cultivated as a vegetable and as a cattle fodder crop in Canada, Britain, and northern Europe, and to a lesser extent in the U.S.