what are tap roots

A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically, a taproot is somewhat straight and very thick, tapering in shape, and grows directly downward. Most dicotyledonous plants, such as dandelions, produce taproots, and some, such as the edible roots of carrots and beets, are specialized for food storage. Upon germination, the first structure to emerge from most seeds is the root from the embryonic radicle, which is a taproot. In plants in which the taproot persists, smaller lateral roots (secondary roots) commonly arise from the taproot and may in turn produce even smaller lateral roots (tertiary roots), increasing the surface area for water and mineral absorption. Some plants, such as the carrot, have a taproot that is a storage organ so well developed that it has been cultivated as a vegetable. The taproot system contrasts with the adventitious- or fibrous-root system of plants with many branched roots, but many plants that grow a taproot during germination go on to develop branching root structures, although some that rely on the main root for storage may retain the dominant taproot for centuries.