And there's this...
They are not decomposers or parasites like many mushrooms. They are symbionts, meaning that the hyphae of their mycelial strands hooks up with the root hairs of trees (in most cases) for a mutually beneficial relationship. They provide nitrogen, phosphorus, and potassium, which they extract from the soil, and increase the water supply to the tree. In exchange, the tree provides stored food energy in the form of carbohydrates (sugars) made in the leaves. As a consequence, the tree grows better, and so does the fungal mycelium. Morels are known to form a symbiotic relationship with 22 species of trees. Here in the Midwest, most of us have probably found them around elms, sometimes around ash trees, and often in old apple orchards. They also have the same relationship with oaks, silver maple, sycamore, cottonwoods, black locust and more. In the SE US, tulip poplar is a dominant tree and the primary symbiont for morels.
around recently dead and dying elm trees than they are around healthy elms, or oaks, or other symbionts. I have a theory that attempts to explain that very thing. It is called the Loss of the Symbiotic Relationship Theory. As the elm dies, so does its root hairs. They no longer provide plant sugars to the hyphae of the morel mycelium. Consequently, the mycelial body senses the loss of the symbiotic relationship as the tree dies. In survival mode, the mycelium sends up a flush of the spore-bearing structures we call morels. Rain, wind, morel hunters, and insects carry the spores out to new locations where they can begin to grow and seek new symbiotic relationships. This happens as the tree is dying. After it has been dead for two years or more, it is very unlikely that morels will still be found at that site. One visual aid that helps us know whether to spend our time looking around a dead elm is to look at the bark. If most of the bark remains on the tree, it is a recently dead elm, and it is worthwhile to look around it. If most of the bark has fallen off, the tree has likely been dead two or more years and it is a waste of time to look there because morels have already abandoned the site. In Michigan, the decline of ash vigor as ash trees are infected by Emerald Ash Borers has led to a similar pronounced fruiting. However, ash trees seem to be dying off faster than elms. One can always hope that other symbiotic trees will become good spots to find morels. Perhaps sugar maple or aspen, for instance. Apple trees are slower to decline than elms or ash, and that is likely the reason why old apple orchards seem to be good places over a long period of time to seek morels.
