Like yams (Dioscorea spp.) and sweet potatoes (Ipomoea batatas) the rutabaga (Brassica napobrassica) and turnip (Brassica rapa) cause considerable confusion because of their similar appearance. However rutabagas and turnips are entirely different vegetables. In fact, the rutabaga is a hybrid of a turnip and cabbage (Brassica oleracea var. capitata). Both are used in similar ways, but there are ways to tell the difference between the two.
Both rutabagas and turnips produce an enlarged root that is harvested and eaten, but the shape of the root differs slightly. While rutabaga are are slightly conical and covered with small hair roots, turnips are smooth and round with a large taproot. As a rule, turnips have white skin and crisp white flesh with muted purple shoulders, while rutabaga skin is yellowish with shoulders that range from green to bright purple, depending on the variety. Rutabaga flesh is generally yellow. While turnip foliage is rough, rutabagas produce waxy, green leaves similar to cabbage.
The foliage from both rutabagas and turnips can be harvested and eaten as green when they are young. The flavor of rutabagas and turnips is similar, but more pronounced in turnips, while rutabagas tend to be sweeter. Both can be boiled, steamed for roasted a a sidedish, and are often served mashed with butter and seasonings. The root vegetables are also used in soups and stews or cooked and served with other roasted vegetables with meat or poultry.
Rutabagas prefer full sun to partial shade in well-drained soil, but do not require high fertility. In fact, according to the Cornell University Extension, too much organic matter or high levels of nitrogen may cause malformed roots in rutabagas. Rutabagas mature in 90 to 100 days and can be stored in a root cellar for winter use. Turnips also prefer full sun to partial shade, but unlike rutabagas, turnips prefer fertile soil rich in organic matter. Poor soil results in stunted growth and poor flavor in turnips. Turnips mature in 30 to 60 days. Both require 1 inch of rain a week and benefit from supplemental watering during hot, dry spells.
The turnip has been cultivated by the Greeks and Romans since before the Christian era and was introduced in America in 1451 by Jacques Cartier, who planted them in Canada. It became a popular garden vegetable in Colonial America. The rutabaga was not introduced until later. It was grown in the royal gardens in England in 1664. By the 1800s it was known as a "turnip-rooted cabbage" in the United States.