This is a good time of the year for mushrooms – and for people who love to look for them.
Mushrooms come in an astonishing variety, and they are everywhere. The photo above shows a clump in a Forest Hills lawn, and you will find them in your garden, in tree beds and in Rock Creek’s woods. After a rain and a warm day, watch to see new ones push up. Then, as it gets cooler in September, different species appear.
Mushrooms are neither plants nor animals. They belong in a different kingdom, the kingdom of fungi, with lichens, yeasts and molds. They have no chlorophyll and cannot photosynthesize to get food. Instead, these organisms feed on organic matter – rotten leaves, dead wood, logs, moss, dead animals, dung, tree roots, compost, acorns, mulch, etc.
One species of oyster mushroom was even found growing on cloth diapers in a Mexican trash dump. Scientists are experimenting to see what other human organic trash this species might recycle.
Please, please don’t eat them.
See that lovely white mushroom above? It is known as the “destroying angel” and it contains a deadly chemical that will kill you. I often see it coming up in our lawns in August. Many other mushrooms are toxic. They may not kill you, but they will make you sick.
Mushrooms come in a fascinating variety of shapes and colors. That also makes them tough even for experts to identify. Don’t assume that a mushroom is safe to eat just because you have enjoyed a similar-looking one in the past.
How mushrooms put down roots
Most of us are familiar with gilled mushrooms, the kind common in the market. The gills contain the spores or “seeds.” The spores develop on the sides of the gills, thousands to a cap.
The purpose of the mushroom is to get the spores dispersed – by wind, rain, or animals. In our area, turtles, squirrels, deer, opossums, foxes, insects, mice, and many insects are fond of mushrooms. Surprisingly, each species of mushroom has its own odor and taste, and this helps attract consumers.
When a spore falls onto promising organic matter, it extends a tiny hypha, or hair-like root (more on that below), and begins to grow. The new organism needs water and nutrients. It is fragile, and as you would expect, the success rate is very low. That is why a mushroom produces so many spores.
These shelf-like mushrooms growing on trees are also mushrooms. They are called bracket fungi, and they are feeding by decaying dead wood. When you see these mushrooms growing on a tree, you know it is dead or dying.
Bracket fungi do not have gills. Their underside is spongy and full of tiny pores. Each pore opens into a tube filled with spores. Experts refer to them as polypores.
This mushroom always reminds me of a pancake. There are a number of polypores like this, which have the common mushroom shape but no gills. Their plain underside is dotted with pores. Several different boletus species are common under oaks in Rock Creek in August and September.
Mushrooms are a key organism in ecology
The really important part of a mushroom is not the fruiting body, but the “roots” or “mycelium.”
The mycelium is a tangled mass of tiny tubes, each smaller than a hair. This is the hypha. The hyphae grow, continually seeking organic matter. When they find it, they secrete a chemical that breaks down the wood or the leaf into chemicals and into elements like potassium and sulfur. These nutrients are “must have” for plants, as well as food for the mushroom organism.
The mushroom above is growing on a railroad tie which sits on a trail in Rock Creek Park. The mycelium of this mushroom is slowly decaying/destroying the wood. The appearance of mushrooms on railroad ties, wooden bridges and fence posts is dreaded by construction workers.
Mushrooms and trees grow together
A symbiotic relationship occurs when two organisms need each other and each one gives something to the other.
A number of mushroom families have a symbiotic relationship with particular trees. The mushroom’s hyphae penetrate the roots of a tree. They provide the tree with soil nutrients as well as vital elements (such as phosphorus, calcium and nitrogen) that other hyphae in the mycelium have obtained by the decay process. In return the tree provides them with the products of photosynthesis – energy-rich sugars and lipids.
We don’t know how many of these symbiotic relationships occur in the plant world, but mycologists say that the chanterelle genus will grow only under certain trees. The one in the photo grows under oaks. Another species requires beech trees. Others need conifers.
Mushrooms, the recycling champions
Without mushrooms and other fungi, the plant world could not exist. And since the animal world depends on plants, it would not be here either. Fungi unlock organic matter so its chemicals and elements can be recycled. Bacteria and other organisms also contribute to decay, of course, but fungi are the champions.
Resources for this article include several excellent sites in Wikipedia, the 1948 Field Book of Common Mushrooms by William Sturgis Thomas (still in print), and a new book, Entangled Life by Merlin Sheldrake (2020, Random House).
The mushrooms pictured in the article were found in this area. Thank you to Betsy Broun, Joy Allchin, Eric Kravetz and Marlene Berlin for the photos.