Mushroom mycelia can take nutrients, especially sugars, from the roots of strong, green plants (like established trees) and "feed" them to weaker understory herbs and seedlings who have less access to light for photosynthesis. A neat example: in the spring, mycorrhizae shunt nutrients from the early trout lily to feed new maple seedlings, while the reverse occurs in the fall. Inter-species nutrient balance is maintained by these fungal networks!
This research continues to increase my respect for the Kingdom Fungi, and I am beginning to suspect that these organisms are the great modulators and networkers of the living world. It is no wonder to me that they are so effective in modulating the function of human physiologies as well, helping to balance immunity and inflammation so effectively. Hopefully more research on this subject will be forthcoming -- it is a field we know woefully little about.
In the meanwhile, Paul Stamets is the man.