By Mary K. Hanson

You see them often in wild areas, especially after a light rain: strikingly brilliant colors against the browns of the forest. They are often mistaken for some kind of fungi, but they’re not; nor are they really plants or any kind of animals. They are the myxomycetes: slime molds.

Starting as nearly invisible single-celled formations born from spores, they can live out their lifespan in a single day. The single cells find one another through a kind of chemical communication system, and congeal into thin amoeba-like globs called plasmodium.

This plasmodium creeps rhythmically along the ground at a speed of about a quarter of an inch per hour over dead leaves, onto stumps or wherever else the motion takes it, pretty much unseen, hunting down bacteria and digestible spores.

When runs out of stuff to eat — or when some other trigger like rain or sunlight excites the mass — the plasmodium finds a prime spot (preferably one that’s dry with a little breeze nearby) to reproduce. It forms fruiting bodies calls sporangia — which can come in a variety of shapes and colors, including red, yellow, gray and bright blue — that go on to produce spores. These spores are then carried off by the breeze and the whole process starts over again.

One of the most common forms of slime mold in this region — and you may even have spotted it in your own back yard — is Fuligo septica. In its excited fruiting-body-stage, this stuff looks like bright yellow froth or thin scrambled eggs. Within a day, though, this mass of froth forms a crust over itself that starts out pearly white and eventually turns brown.

Underneath the crust, the spores are forming. When the crust is brittle enough, it will break at the slightest provocation, releasing the spores.

If you find this in your back yard, don’t worry. It’s a bacteria-eater and won’t affect your grass or plants. Some folks try to get rid of it by spraying it with a hose, but all that does is spread the mold further over your lawn and plants. So, it’s best just to let it be and run its course.

Two other forms of slime mold prefer weather that’s slightly chilly, and I’ve been able to find them often in riparian (river-side) habitat throughout the region. They are wolf’s milk slime mold and white-finger slime mold.

The wolf’s milk variety appears as bright pink “buttons” or cushions in its early stages, and then turns a shiny brown as it matures and goes to spore. Touching one of the young buttons will make pink-colored toothpaste-like “milk” ooze from it.

The white-finger variety of slime mold, on the other hand, starts out looking like strings of tiny white upright fingerlings. Look more closely, and you’ll see that each tiny finger is actually sitting on top of a thread-like stalk. As the fingerlings age, they turn brown and then shiny black.

Once in the spore-bearing stage, the molds go brittle, and interestingly enough, even though the wind, critters and people can promote the spread of the spores, some slime molds actually depend on beetles to help spread the spores. The beetle’s hard feet and legs pierce through the “crust” that surrounds the spores, and the bristles on their legs carry the spores to new destinations.

The best time to find active slime molds is right after a rain — so in drought years like this one, finding them might be difficult, but keep an eye out for them anyway. When you encounter them, remember that the time between “fruiting” (when they’re most visible) and going to spore can sometimes take less than a day. They won’t be around for long, so take as many photos of them as you can whenever the opportunity presents itself.

— Tuleyome Tales is a monthly publication of Tuleyome, a nonprofit conservation organization based in Woodland. For more information about Tuleyome go to www.tuleyome.org. Mary K. Hanson is an amateur naturalist and photographer and author of “The Chubby Woman’s Walkabout” blog. 

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