A
patron came in and described something that had appeared on their lawn
overnight. At first, they’d thought a dog had been sick in their yard, but on
closer inspection it seemed to be an ugly yellow fungus. The patron reported
that when it rained, the mass released a smoky-looking cloud of spores. It also
appeared to bleed.
We
had noticed something similar growing in the mulch in front of the library a
few weeks earlier. It had eventually disappeared on its own, and we’d never
tried to identify it, but we knew what our patron was describing. Because we
thought the yellow mass might be a fungus, we checked The Audubon Society Field Guide to North American Mushrooms, David
Arora’s Mushrooms Demystified, and Peterson’s Field Guide to Mushrooms. However,
we couldn’t find what we were looking for.
Searching on Google for an image of yellow fungus led us to an article by Susan Mahr on the Wisconsin Master Gardener Program website. There were several pictures that
our patron recognized as the organism growing on their law, which the website
identified as the “dog vomit slime mold.” Technically, it’s not a fungus at
all. While scientists used to place slime molds in Kingdom Fungi, they were
moved to Kingdom Protista, which serves as a catch-all for eukaryotic organisms
that are not plants, fungi, or animals.
According
the Mahr, the dog vomit slime mold begins its life as a spore. These spores
develop into cells, which join up to form the slimy-looking yellowish-brown
plasmodium. The plasmodium creeps across the land, consuming the bacteria and
other organisms that thrive in decay. When it runs out of food or gets too dry,
the plasmodium transforms into an aethelium, or a “fruiting body” – the puffy
yellow mass that will release spores and begin the cycle anew.
The
aethelium will continue to develop, hardening and darkening in color. It may
start to liquefy in spots, which can make it appear to bleed, as our patron
noticed. Once the hard crust is broken, it will release its clouds of spores.
This may have been the “smoking” that our patron noticed.
Despite
its unappealing name and appearance, the dog vomit slime mold is almost
entirely harmless. (The spores may aggravate asthma or allergies.) It will
eventually dissolve on its own after a few days, though it can also be broken
up. A slime mold needs moisture, so they’re usually spotted in hot, humid
weather. Watering less, or raking up damp mulch, can be another way to be rid
of them.
