Which component is NOT a part of the root system?

The axillary bud is not part of the root system; it is associated with the shoot system of a plant. Axillary buds are found in the leaf axils (the angle between the upper side of a leaf and the stem) and can develop into branches or flowers.

In contrast, the components that are part of the root system, such as the taproot and lateral roots, function primarily in anchoring the plant and absorbing water and nutrients from the soil. The taproot is the main root, which can grow deep into the ground, while lateral roots branch off from the taproot to increase the surface area for absorption. Rhizomes are horizontal underground stems that can also contribute to the root system by producing new shoots and roots. Understanding the distinct roles these components play helps clarify why the axillary bud is classified differently.