What’s that in the middle of the lawn? They look like mushrooms. If you’ve had a tree cut down in the past few years, they probably are. It may not be in the forefront of your mind, but a tree’s root system is roughly the same size at the trunk and canopy put together. When a tree is cut down and the branches are hauled away, the material quickly leaves the space and our minds, but the roots remain.
Once the tree is no longer actively growing in the landscape, the roots slowly begin to decompose. As they do, their mass of carbon is converted into humus by Mother Nature, specifically, various soil inhabiting fungi. Bit by bit, the solid root wood is softened in the process, sometimes producing above ground fruiting bodies called mushrooms.
Sometimes, mushrooms are seen in the lawn without a tree removal from the landscape, however, the same process is taking place – a piece of carbon is being transformed into humus/organic matter by fungi. In most cases, if you’re able to track it down, a piece of lumber or construction debris or simply a high percentage of naturally occurring soil organic matter is being decomposed.
Because the decomposition process requires sunlight, warmth and moisture, mushrooms in the lawn are most commonly seen a few days following a rain event or lawn sprinkler application. One final note: because mushrooms are associated with several different species of fungi, it’s impossible to tell if they are poisonous without being identified by an expert mycologist. As such, they should be left alone and not eaten. Most are harmless, but it’s best to be on the safe side.