June “Plant” Profile: Discovering Slime Molds

This month, instead of profiling a plant, we’ll be profiling a completely different kind of organism… slime molds!

In the fall of 2015, the Elisabeth C. Miller Library at the Center for Urban Horticulture held an art exhibit about slime molds: Now You See It, the Slime Mold Revelation! I had never head of these organisms and was intrigued by the art display and the amazing enlarged photographs of their fruiting bodies. But I still didn’t quite get what slime molds are.

My next encounter was about a year later; I was giving a tour in the Washington Park Arboretum and was approached by our Arborist, Clif Edwards, who said, “Hey, Catherine, I just found some awesome Dog Vomit Slime Mold yesterday!!”   (This is one of the reasons I love the Arboretum, by the way.) My tour group was excited about this too, and we set out to find the slime mold as directed.  Unfortunately when we found it, it had already dried out.

Dried out slime mold with spores. Photo by Flickr user shaviro.
Dried out slime mold with spores. Photo by Flickr user shaviro.

Here’s what it looks like when it is in a living aggregated mass:

Fuligo septica by Flickr user Scot Nelson
Fuligo septica by Flickr user Scot Nelson

 

In 1973 a housewife in Texas found a living blob in her yard and called the authorities, it became a big news item nationally and caused much consternation as people tried to figure our what it was – some even theorizing that it was an alien invasion.

The appearance of the aggregated mass is where slime mold gets its common name. Its scientific name is Fuligo septica. Originally thought to be fungus, it is now known that slime mold organisms predate fungi on the evolutionary ladder and are a separate kingdom called Protistas.

There are over 500 species of slime molds. Most of the ones we see are categorized as myxogastrics and are macroscopic like the Fuligo septica. These organisms are still being studied and classified by scientists.

Basically, slime molds are eukaryotic single-celled organisms, which can live freely as single cells and spend most of their time in this state. When their food (microorganisms found in decayed organic matter) becomes scarce, they emit a chemical trigger and they begin moving toward each other to aggregate and form a multi-cellular reproductive structure. This stage is basically a large, jello-like “blob” that lives for about a day producing stalks with fruiting bodies.  After these fruiting bodies develop spores, the “blob” dries out and then releases its spores into the air to spread and start all over again.

Phylogenetic Tree of Life from Wikimedia Commons
Phylogenetic Tree of Life from Wikimedia Commons

I hope to find a Fuligo or other slime mold this summer in its aggregate state – in the meantime, I found this great three-minute tutorial on YouTube, which includes time-lapse footage of the cells moving together and forming the mass. Check it out!

Common Name: Dog vomit slime mold, scrambled egg slime, or flowers of tan
Scientific Name: Fuligo septica

References:

http://www.ucmp.berkeley.edu/protista/slimemolds.html
The Creeping Garden; irrational encounters with plasmodial slime moulds, Sharp & Grabham, Alchima Press 2015
Wikipedia
https://botanicgardens.uw.edu/about/blog/2015/09/04/art-exhibit-now-you-see-it-the-slime-mold-revelation/