Carrots
In modern times, an orange vegetable, but during medieval times, was ( I believe) known to most people in antiquity as a white vegetable (like a turnip, but tasting like a carrot) but also (less common?) red, reddish black, orange, yellow and various other shadings were mentioned, especially in the late medieval period.
Carrot grows as a conical root in he ground.
Carrots were eaten raw or cooked in medeival times. Various alcoholic beverages can also be made from carrots, but St Ursula's "carrot wallop" should definately be avoided (unless it's improved lately).
"They (carrots) remain in the human bile gland awaiting a time to be thrown up. Not a nice vege at all."
Various other medieval names exist for carrots, or that include carrots, eg skirret (water parsnip), pasternakes (carrots or parsnip).
more details on varieties of root vegetables at:----
http://www.florilegium.org/files/FOOD-VEGETABLES/root-veg-msg.html
recepies for carrots:----