Mushroom of the Month - February 2010
Galerina autumnalis and G. marginata:
the Deadly LBMs (little brown mushrooms)
Mycologists, amateurs and professionals alike, use a term for small off-white to dark brown mushrooms that are hard to identify. That term is LBMs: Little Brown Mushrooms. The term is akin to one used by birders: LGBs or Little Gray Birds. Among to LBMs two species particularly stand out because they are deadly poisonous having the same poisons, phallotoxins and amatoxins, that make some species in the Amanita genus deadly poisonous.
The cap of the Galerinas is broad and convex about 1 to 2 ½ inches across, has a smooth surface, is somewhat sticky when wet, and ranges from a light yellowish tan when dry to dark brown when wet. The gills are attached sometimes with a small tooth going down the stalk, they are yellowish brown when the mushroom is young becoming rust brown with age. The stalk is 1 to 3 inches long and 1/8 to ½ inches wide. It is hollow whitish above and brownish to blackish at the base often with the lower part covered with white mycelium. There is a partial veil which often forms a thin white ring on the stalk with age the ring darkens. The spore print is rusty brown. Galerina marginata often loses its ring.
The Galerinas are wood decayers and often grow on rotting wood and debris of both hardwoods and conifers. They occur both scattered and in clumps. They are fairly common and definitely occur in Michigan.
The occurrence of these deadly mushrooms leads us to strongly recommend that amateur mycologists avoid all small mushrooms that grow on moss or on wood and have thin, brittle stalks. There is an edible look-alike, Pholiota mutabilis but we would not recommend trying it.