If you look very closely at dead wood as you're walking through a forest, you might find something that looks a bit like the a cluster of nests made by a miniature bird. Look even closer, and you'll notice that the pinky nail-sized cups are filled with "eggs."
These tiny structures are actually the fruiting body of a fascinating fungus.
There are around 31 species of the appropriately named bird's nest fungi in North America. The cups grow out of decaying wood covered by little caps. When the caps fall off, the collection of seeds inside is exposed, and for the fungi, spreading those seeds is just a matter of waiting until the next rain.
"The nests are called 'peridia' ('peridium' in the singular), and serve as splash cups," notes Michael Kuo of Mushroom Expert. "When raindrops strike the nest, the eggs (called 'periodoles') are projected into the air, where they latch onto twigs, branches, leaves, and so on."
The seeds (or spores) eventually develop their own structures, and the cycle of creating fruiting bodies and splash-ready seeds begins again.
For a long time it wasn't known exactly how the seeds were dispersed. In fact, French botanist Jean-Jacques Paulet proposed in 1790 that the cups had some sort of spring mechanism for ejecting the seeds. But, the patience to wait for a good rain is all that's needed. In fact, some species are shaped in such a way that a raindrop hitting at a good angle can launch a seed as far as 1 meter away from the cup!
In the photo above, note how the cups on the left are still wearing their caps, and seeds from the open cups have been splashed out of the cup by rain.
The many different species of bird's nest fungi vary in cup size, seed size, color, texture and more. Some can look like dark purple flowers holding black pearls, while others look more like clay cups holding little gray coins. Even with the diversity of appearance, you'll always know whether or not you're looking at a bird's nest fungi thanks to its distinctive shape!
And don't worry if you find them in your garden; they don't do any harm to plants and actually help break down organic matter for an even healthier garden. Plus, they add a bit of fairy-land appeal to your yard!
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