Plants have three organs: roots, stems, and leaves. Growth, flowering, food production, and storage all depend on the activities of these three organs. The combination of stems and leaves makes up the shoot system that is usually visible because it grows above the ground and gives rise to flowers, fruits, and seeds. Roots, on the other hand, are often underground, but the root system can be every bit as massive as the aboveground shoot system. An active root system makes it possible for the plant to carry out growth, photosynthesis and other chemical reactions, branching, flowering, fruiting, and seed production.

Roots are so critical to plant survival that a sprouting seedling devotes its first days to root growth before allowing leaves to pop out of the seed. During this time of early germination, the root anchors the plant in the soil and begins to deliver a reliable water...