Turnip or parsnip are both ROOT vegetables that belong to the same family of plants, known as the Brassicaceae family. The turnip is a ROOT vegetable with a white flesh and a purple-tinged skin, while the parsnip is a ROOT vegetable with a creamy white flesh and a yellowish-brown skin. Both vegetables have a sweet, earthy flavor and can be eaten raw or cooked. They are both high in fiber and vitamins, making them a healthy addition to any diet. The four-letter answer to the crossword clue is ROOT, which accurately describes both turnips and parsnips.