Most carrots are sold without the tops because they have been shown to draw moisture from the roots. Yet many people buy carrots with tops to ensure the product is fresh. However, in order to store carrots longer, remove the tops.
Carrots belong to the parsley family. They originated in Afghanistan, cultivated originally for medicinal purposes utilizing the seeds which are produced in the second year of this biennial plant. (Marketable roots grow in a single season.)
The use of carrots spread westward, introduced into England from Holland in the 15th Century. At that point, carrots were coveted for their tops, and no well-dressed English gentlewoman would be seen without lacy carrot leaves decorating her hair.