Tom Volk's Fungus of the Month for May 2000

This month's fungus is Agrocybe praecox, a spring mushroom of bark mulch and decaying wood.

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Agrocybe praecox This month's fungus is a common inhabitant of bark mulch or wood chips. It's not the most attractive fungus in the world, but it does have its charms. The brownish tan color of Agrocybe praecox (ag-ROSS-ih-bee PRAY-cox) fruiting bodies makes them difficult to see against the mulch, but they seem to show up better when it's wet. It can sometimes be found in large quantities in the spring, especially when you're looking for morels, which may also show up abundantly in bark mulch -- if you're very lucky. We commonly find both Agrocybe and morels in the mulch here on campus at the University of Wisconsin-La Crosse. I've also found them both in abundance on campus at UW-Madison where I got my Ph.D.

Last year when I was hiking in the woods with Anna Gerenday and Toby Feibelman in Minnesota we found literally *thousands* of Agrocybe praecox fruiting bodies lining both sides of a wood chip path through the woods (but not too many morels). The picture is just below. Also unfortunate for us is the fact that most Agrocybe species are not considered good edible mushrooms. Agrocybe species have a dark brown spore print and usually have a partial veil, which protects the developing gills then leaves a ring around the stalk after the cap opens.

Agrocybe praecox on a tree-- Hal Burdsall's picture

The location of the fruiting bodies growing on wood leads one to believe this is a wood decay fungus, which in fact it is. (sometimes you can follow your instincts...) See this page for a discussion of white and brown rots. Briefly recounted, the main components of wood are cellulose and lignin, with some glucans and other materials acting as glue. Brown rot fungi digest the cellulose and leave the brown lignin behind; white rot fungi (in their simplest form) digest the lignin and leave the white cellulose behind. I believe Agrocybe species cause a white rot. The easiest way to find this out is to post it here on the internet and wait for the criticisms to come in or not....

Agrocybe aegerita growing with bald cypress in Louisiana The species of Agrocybe are very difficult to distinguish, based mostly on their habitat, geography, and spore characteristics. In our area we also have Agrocybe sororia, commonly growing in the mulch and wood chips. Agrocybe dura is another common species usually found in grass. One species, Agrocybe aegerita, shown to the left, is actually a delicious edible mushroom and is being cultivated commercially on a relatively small scale. One common name for this is the "Louisiana Roman Mushroom" -- but we all know the problems with common names, don't we? It's all about marketing these days. Agrocybe aegerita grows in the deep south of the USA and probably into Mexico and the Caribbean. I've only tasted it once from the wild, but I was very impressed by its flavor and texture. It usually grows in nature on solid wood, and usually leaves part of its veil as little skirtlike overhangs on the cap, as well as leaving a ring on the stalk.

Agrocybe praecox bases

I hope you enjoyed reading about and looking at this month's fungus. You've probably got some growing in your bark mulch or wood chips right now. I don't recommend that you eat them however. But it's nice to look at *real* fungi after a long winter of just looking at pictures on the internet!

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