Lateral root

Lateral roots, emerging from the pericycle (meristematic tissue), extend horizontally from the primary root (radicle) and over time makeup the iconic branching pattern of root systems. They contribute to anchoring the plant securely into the soil, increasing water uptake, and facilitate the extraction of nutrients required for the growth and development of the plant. Lateral roots increase the surface area of a plant's root system and can be found in great abundance in several plant species. In some cases, lateral roots have been found to form symbiotic relationships with rhizobia (bacteria) and mycorrhizae (fungi) found in the soil, to further increase surface area and increase nutrient uptake. Several factors are involved in the formation and development of lateral roots. Regulation of root formation is tightly controlled by plant hormones such as auxin, and by the precise control of aspects of the cell cycle. Such control can be particularly useful, as increased auxin levels help to promote lateral root development, in young leaf primordia. This allows coordination of root development with leaf development, enabling a balance between carbon and nitrogen metabolism to be established. The general zones of the primary root (taproot) that gives rise to eventual lateral roots are presented below from top to bottom. The most mature and developed tissue is found near the top, while the newly dividing cells are found near the bottom. Maturation Zone: Cells in this stage have developed differentiated characteristics and have completed maturation and elongation. The xylem system is seen to develop in this zone along with lateral root development. Elongation Zone: Cells in this stage are rapidly elongating and parts of the phloem system (sieve tubes) start to develop. As you move up closer to the maturation zone, cell division and, elongation decrease. Meristematic Zone: Right above the root cap and contains the "stem cells" of the plant. In this zone, cells are dividing quickly and there is little to no differentiation present.