Fine roots are plant roots that have a diameter of two millimeters or less. They are mainly involved in acquiring soil resources, such as water and nutrients, and transporting them to other parts of the plant. Fine roots are similar to the leaves and twigs of the shoot system in terms of their function. Fine roots can vary in their traits and strategies depending on the species and the environmental conditions. Fine roots can also be classified into subcategories based on their diameter, position in the root system, and primary function.
Some examples of trees that have fine roots are white oak, walnut, hickory, black gum, sassafras, sweet gum, Japanese pagoda, butternut, and pine. These trees have developed deep and robust taproots that can reach the water table and withstand drought. The taproot is the first and main root that emerges from a germinated seed. The taproot can produce lateral branches that also have fine roots. The fine roots of these trees can penetrate rocks to extract minerals that the tree needs.