New root hairs are constantly forming at the tip to replace the older ones dying further back. Root branching occurs irregularly. Nodes are not present on roots. When a root tip is removed by pruning, new roots form and branching occurs. Under appropriate conditions, shoot buds form on roots.
Some plants form shoot buds easily and the plant becomes a pest.
The original root from a seed is the primary root. When the primary root becomes the main root of the plant, as in the oak and hickory, it is called the taproot. Under natural conditions, taproot systems are not as branched as other root systems. Removing the root tip encourages branching. The concept that roots radiate out from the crown like the spokes on a wheel and penetrate to a given depth is obviously more fancy than fact.