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What is Bird's Nest Fungus?

Late summer is the time I see a very special fungus growing along the trail in Joyce Kilmer Memorial Forest. You have to look very closely. This delicate little organism is so small that it is very easy to miss. It is called “Bird’s Nest Fungus”. It belongs to the family of Nidulariaceae with ‘nidulus’ meaning a small nest.

This tiny fungus looks like what its name implies, a tiny cup-shaped bird’s nest with little eggs resting inside the nest. In fact, the spheres are the method through which the organism reproduces itself. The cup shape is actually the fruiting body of the fungus and holds the tiny peridioles (that look like tiny eggs). The peridioles contain the spores, which are how this tiny fungus reproduces. Typically, the nests have from five to eight tiny “eggs”.

Rasbak, CC BY-SA 3.0 <>, via Wikimedia Commons

Bird’s nest fungi catch rain or dew in the little fruiting cups, which are about ¼ inch in diameter. When a splash of water hits the peridioles the little egg-like spore containers are knocked out of the “nest” and fly through the air, sometimes as far as four feet! They have a sticky membrane which catches onto whatever it happens to land. It could be a plant stem or the side of a tree, just whatever it hits after being knocked from the cup. Once the stuck peridiole dries out, the spores are released, hopefully in an acceptable location for a new bird’s nest fungus to grow.

According to my research, bird’s nest fungus is a saprophyte, and they break down organic waste matter into rich compost. They take nutrients from the material they grow in and cause decomposition to increase nearly two-fold. In your garden at home, this means cleanup is much quicker with fungi and other decomposers in the landscape. Bird’s nest fungus in heavy bark mulch is especially helpful. They help reduce large chunks into easy to break down slivers that help enrich the soil and increase tilth. claims that “The Bird’s nest fungi were first described by Carolus Clusius, a Flemish botanist in 1601 in a book called Rariorum plantarum historia. Originally, incorrectly, the little eggs were thought to be fungi seeds. Fossilized remains of some bird’s nest fungi found in the Baltic and Dominican Republic show that some of their basic characteristics were developed 40 to 50 million years ago.

People often ask me whether a fungus is edible. These tiny nests (splash cups) are not thought to be poisonous and their size makes them impractical to harvest. Some research has indicated that they may have antibiotic properties against bacteria but facts are sparse at this time.

The Joyce Kilmer Memorial Forest is the perfect place for this kind of fungus. It is moist and it is cool and damp (most of the time). They are a delightful fungus to show to your children and are most obvious in the fall of the year, but you have to search for them closely in the soil along the trail.

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