taproot

thumb|The two types of root systems in plants. The fibrous-root system (A) is characterized by many roots with similar sizes. In contrast, plants that use the taproot system (B) grow a main root, with smaller roots branching off. The letters indicate where the root systems begin.

A taproot is a large, central, and dominant root from which other roots sprout laterally and horizontally. Typically, a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot is a storage organ so well developed that it has been cultivated as a vegetable.