The roots of a commercial vineyard originate from the roots that develop at the base of cuttings, which are more divided than the tap-root style of a seedling’s root system. The position and number of the main framework roots, the ‘spreaders’ which extend out and down, are determined during the first three years. Although most vine roots occur in the top metre of soil (less if unfavourable soil horizons impede their penetration), there are many examples where roots have penetrated to 6 m/20 ft or more; often these examples are found in dry conditions such as the douro Valley. The root framework supports a large number of fibrous roots which, by their continuing growth, explore the soil for minerals and water. Root density is highest in friable soil with continuing supplies of minerals, water, and oxygen. mycorrhizal fungi play an important role in increasing the surface area of the roots.