Spreading

Unlike the taproot, the lateral roots usually grow parallel to the soil surface. In temperate regions, they can extend two to three times beyond the branch spread, even four times in drier soil. An oak tree's lateral roots, for instance, can stretch 30 metres from its trunk.

For fun, pick a tree growing in your yard or a park. Estimate its branch spread, then start from the base of its trunk and pace off three times that distance. You may still be standing on top of its roots!