The two main types of root systems are taproots and fibrous roots. A taproot consists of a single large, central root with smaller side roots, while fibrous root systems consist of networks of many small roots.
Common examples of plants with taproots include carrots and beets. As plants with taproots grow larger, their roots grow straight down into the ground in order to gain access to more water and nutrients. Shorter, thinner roots, known as lateral roots, protrude from the sides of some taproots to help hold them in the ground. Lateral roots arise from the pericycle, which is the central portion of the root, allowing the water that they absorb to be passed directly into the main root and up to the rest of the plant.
Examples of plants with fibrous root systems include grasses and trees. As these plants grow, they expand their root systems over the surface of the land, rather than reaching further down. Networks of fibrous roots can be extremely extensive; the roots of one grass plant may be more than 100 miles long when laid end-to-end.
In addition to fibrous roots and taproots, there is also a third type of roots known as adventitious roots. These are roots that emerge from an above-ground portion of the plant, such as from a stem or leaf. Plants with adventitious roots also have either a taproot or fibrous root system in addition to their adventitious roots.