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The Turnip Disambiguation Page

Patrick Nielsen Hayden sends us to the Turnip Disambiguation Page of Wikipedia:

Turnip (disambiguation) - Wikipedia, the free encyclopedia:

Scientific term Brassica rapa rapa Brassica napus or B. napobrassica Pachyrhizus
Southern England, most Commonwealth countries turnip swede (= Swedish turnip) yam bean
United States turnip rutabaga or yellow turnip jicama
Ireland and Northern England turnip swede  
Scotland swede, tumshie or white turnip turnip or neep  
Cornwall white turnip turnip  
Malaysia, Singapore, and Philippines     turnip
Atlantic Canada   turnip jicama
also called white turnip or summer turnip yellow turnip or winter turnip sweet turnip

Brassica napus and B. napobrassica are called swedes (a shortening of Swedish turnip) in England, especially in the South, and in most dialects of the Commonwealth. Rutabaga is mostly an American word. The rutabaga or swede differs from the turnip (Brassica rapa) in that it is typically larger and yellow-orange rather than white.

However, in some dialects of British English the two vegetables have overlapping or reversed names. In the north of England and Scotland, the larger, yellow rutabagas are called neeps (from an Old Norse term, not a shortening of "turnips"), or turnips from folk etymology, while the smaller white turnips are called swedes.