Linked from
The 7 pages that link to Turnip, each with the reason it gives.
Brassica rapaBroader topic: Turnips are a major root-crop form of the species.
BrassicaBroader topic: Its enlarged storage root is a distinct edible form within the genus.
CauliflowerCompared with: Turnip is a different Brassica crop, eaten mainly for its swollen root.
DaikonCompared with: Turnips resemble daikon in some dishes but belong to a different crop group.
KohlrabiCompared with: Turnips resemble kohlrabi in shape, but the edible portion is a root.