"Myco" means mushrooms, "rhizal" means roots.

The collection of filaments of cells that grow into the mushroom body is called the mycelium. The mycelia of these mycorrhizal mushrooms can form an exterior sheath covering the roots of plants and are called ectomycorrhizal. When they invade the interior root cells of host plants they are called endomycorrhizal. In either case, both organisms benefit from this association. Plant growth is accelerated. The resident mushroom mycelium increases the plant's absorption of nutrients, nitrogenous compounds, and essential elements (phosphorus, copper, and zinc). By growing beyond the immediate root zone, the mycelium channels and concentrates nutrients from afar. Plants with mycorrhizal fungal partners can also resist diseases far better than those without.