Usually it emerges from the seed before the embryonic shoot, or plumule, its tip is protected by a root cap, or calyptra, as it pushes through the soil. Roots that branch from the primary root are called secondary roots.
In many plants the primary root is known as a taproot because it is much larger than secondary roots and penetrates deeper into the soil. Beetroots and carrots are examples of plants with very large taproots adapted for food storage.

The radicle may form the basis of the entire root system, or it may be replaced by adventitious roots (positioned on the stem). Grass embryos have a single radicle, but in addition, several other seminal roots form just above radicle; these roots later branch and form a fibrous root system.