We all learned at an early age that plant roots serve to anchor the plant and absorb water and nutrients from the soil. It might surprise some of you, but the absorption part needs revising.
Mycorrhizae are fungal associates of plant roots. A few decades ago, these fungi were not well understood. They had been documented in a few plants, mostly trees, and were considered to be rather unusual. But as scientists studied the fungi and associated plants more closely it was discovered that some of these mycorrhizae grew around the roots while other species actually grew into the plant roots. The two forms of mycorrhizae are called ectomycorrhizae (“ecto” meaning outside) and endomycorrhizae (“endo” meaning within).
We now know that the endomycorrhizae, those that grow into the plant roots, form symbiotic relationships with around 80% of all vascular plants. These plants occur in both wild and domestic plants, trees, shrubs, and herbaceous plants, and members of most plant families. They benefit the plant by basically trading water and essential nutrients such as phosphorus in exchange for sugars. They also are known to help protect the plant against diseases and nematodes.
More recently scientists discovered that some of these endomycorrhizae in forested areas form networks in the soil that not only connect to the roots of certain species of plants, but also to those of different species. So these mycorrhizae may be enabling the flow of water and nutrients between many (maybe most) of the trees in a forest. These relationships are a lot more complex than we had thought. It has been suggested that perhaps 80% or more of the nitrogen and phosphorus in these plants may be obtained through mycorrhizae.
Mushrooms of course are the fruiting structures of fungi. And some of those mushrooms may be mycorrhizal species. So, as you see all those mushrooms popping up in the woodlands, groves and shelterbelts, and other places this summer, consider that they may be providing underground conduits for the movement of water and nutrients between the trees, and perhaps some other plants in the area. Roots may be still functioning in absorbing water and nutrients, not all directly from the soil, but from mycorrhizae in the soil.