Practically every fungal species of culinary interest is either mycorrhizal (growing underground in symbiosis with the roots of living trees) or saprotrophic (feeding off dead wood or other decaying plant matter.) Beginning mushroom hunters may not realize how important that knowledge of these relationships is to the success and safety of mushroom forays.
If one has a particular target species of mushroom in mind, it is very helpful and in some cases mandatory to know what sort of tree to seek out. For example, if you are looking for the delicious and coveted Barrows’ bolete, Boletus barrowsii, then you will not find it anywhere in Arizona except under a Ponderosa pine tree (Pinus ponderosus.)
Conversely, knowing what sort of tree an unknown mushroom fruiting body was associated with may simplify the job of identifying it as to species. A member of the Leccinum genus found in a grove of quaking aspen (Populus tremuloides) is very likely to be an aspen bolete, L. insigne.
It is also worth remembering that some species may be toxic when collected from certain tree species but not others. For example, the Chicken of the Woods (Laetiporus sulphureus) is thought to be more likely to cause gastric upset if it is found growing on a tree of the genus Eucalyptus, versus other species of wood.
Finally, many people who are enthusiasts of mushroom foraging may also find it of interest to learn which trees can be harvested for edible products of their own. The Piñon pine (Pinus edulis), for example, grows at 4000 to 6000 feet all over the state, and produces a crop of delicious pine nuts in the autumn each year. The Navajo Indians collect them in large quantities, and one of the simple pleasures of living in Arizona is buying them at trading posts and roadside roasting stands when crossing their reservation. Why not learn to recognize the tree, and pick some of its nuts yourself when you are coming down the hill from a late-season mushroom foray?
Luckily for Arizona mushroom hunters, there is now a small field guide specific to our native trees that can help you in all of these situations. This book is called, rather unimaginatively, the “Trees of Arizona Field Guide“, by one Stan Tekiela. It is small, light, and well organized by leaf/needle shapes and numbers. I’ve found it very instructive and useful, and it has earned a spot in my backpack for mushroom forays.
I grew up outside Prescott, spending plenty of time in the outdoors, but until I read this book I did not know that there were three or four different species that fall under the heading of what we always called “blackjack oak.” Nor did I realize that most of the trees we called “spruce” were actually firs. I know the difference now, thanks to this useful guide. It also helped salvage an early season trip I took last summer, when there was not much fungal fruiting going on, but plenty to be learned by going around the forest with this guide in hand.