What type of root structure consists of a large central root with many smaller roots branching out?

The type of root structure characterized by a prominent central root that extends deeply into the soil, with numerous smaller lateral roots branching off is known as a taproot system. This structure is typical of many dicotyledonous plants, wherein the primary taproot grows directly downward, anchoring the plant firmly and allowing for the absorption of water and nutrients from deeper soil layers. The branching roots that arise from the primary taproot contribute to the overall stability and nutrient absorption capabilities of the plant, making it more resilient in varying environmental conditions.

In contrast, fibrous root systems are characterized by a network of thin, hair-like roots that spread out near the surface of the soil, lacking a dominant central root. Adventitious roots can arise from unusual locations on the plant, such as stems, and do not follow the typical taproot or fibrous pattern. Bulbous roots, often associated with underground storage structures like bulbs, do not fit the description of a central root with branching smaller roots. Therefore, the taproot system is the most accurate description of the specified structure.