Final answer:
The cortex, which is a layer of ground tissue in a plant's root, often stores starches and other photosynthetic products as an energy reserve.
Step-by-step explanation:
The ground tissue of the root, also known as the cortex, often stores photosynthetic products, which primarily include starches. The cortex, located between the epidermis and vascular tissue, serves as a storage area within the plant's root system. In contrast, the pith, situated between the vascular tissue and the center of the root, has a similar function but is less prominent in roots compared to the cortex.