Roots have no regular branching pattern like the shoots which develop at nodes from buds in the axils of leaves. Lateral roots arise from tissue on the outside of larger roots. The root cap protects each root tip as it is forced through the soil by elongating tissue just behind the tip of the root. Just back from the root tip are the root hairs which are fine outgrowths of single cells. Water and nutrients are absorbed through root hairs and by the tips of these smallest roots.
Root hairs are functional for a few weeks to two years and then are sloughed off.
Most tree species are infected with mycorrhizae. Mycorrhizae are specific fungi which form a symbiotic relationship with a tree. These fungi receive their nutrition from the host plant to complete their life cycle and aid the host plant by increasing the efficiency of the tree s root system. Trees can share root systems. If two roots of the same species grow next to each other, as they grow in diameter, they may grow or graft together.