The invasion

At the beginning of each Spring, I tend to meticulously inspect my beds for any signs of life. Three weeks ago upon one such inspection, I noticed something odd. A hive-like structure had developed within a portion of exposed mulch...

 This mysterous structure had emerged within a bare exposed portion of mulch that had been under deep snow cover for most of the winter.

This mysterous structure had emerged within a bare exposed portion of mulch that had been under deep snow cover for most of the winter.

 "Just what exactly is this thing?" I asked myself. "Could it be some kind of insect's nest?" Immediately I regretted not knowing more about common Iowa insects and their wintry dwellings. I reached out to touch them, the circular rims were flexible, and somewhat slimy. I noticed what appeared to be black 'eggs' inside each tube--oh dear--there were hundreds of eggs. A chill ran down my spine, "I need to nip this invasion in the bud. Wouldn't want some colony of bizarre underground bugs overrunning my garden this Spring." I ran back in the house and immediately went to task, searching for 'underground insect hives', or 'attack of the evil mulch snatchers'. Nothing.

Then an idea struck. What about a fungus? Just a few clicks of my mouse and, bingo! Ladies and gentlemen, I give you Cyathus olla, the Bird's Nest Fungus!

 Notice the round peridioles scattered about on the mulch surface (LEFT). Eventually these will split to release their spores.

Notice the round peridioles scattered about on the mulch surface (LEFT). Eventually these will split to release their spores.

The Latin words 'Cyathus' (chalice) and 'Olla' (cooking pot) were used to name this fungus for its peculiar shape. Bird' Nest Fungus has a fruit body, or peridium, resembling a chalice or nest, whichever you prefer, which is filled with smooth circular black 'eggs' called peridioles.

The 'nest', or splash cup, enhances the force with which rain drops strike, making the spore-filled peridioles explode out as far as 30 inches into the mulch even under the slightest rain. It can also reproduce sexually via meiosis.

If you find this critter in your mulch, worry not!  Bird's Nest Fungus is non-pathogenic. In fact, it can only feed on diseased wood, so it is doing you the service of breaking down the mulch into nutrients that can be absorbed by plants.

Looks like I'm in for free fertilizer for a few years! Phew...