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Plasmodium

Wolf’s Milk Slime Mold Fruiting

If you examine rotting logs after a rain between the months of June and November, it’s likely you eventually will find what looks like a cluster of tiny (under ¾”), pinkish puffballs growing out of the surface of one or more logs.  Although these growths resemble fungi and were at one time classified as such, they are now classified as slime molds, some of the world’s strangest organisms.  Long mistaken for fungi, slime molds are now classified as a type of amoeba.

The name of these pink balls is Wolf’s Milk Slime Mold, or Toothpaste Slime (Lycogala epipendrum).   They are one of the most frequently noticed slime molds in North America, probably due to the bright color of the young fruiting bodies (aethalia).  The common names derive from the paste-like pink substance found inside of them.  As the fruiting bodies age, both their exterior and interior turn purplish, then gray or brown (see photo inset). At maturity the paste develops into powdery grey spores.

When not fruiting, single celled individuals move about as very small, red amoeba-like organisms called plasmodia.  When certain conditions change, the plasmodia convert into the pinkish, spore-bearing structures seen this this photograph.

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