Chicken of the woods

Posted: Sunday, August 16, 2009

One of the most colorful sights in our forests in late summer is a shelf fungus known as chicken of the woods, or sulfur shelf.

It forms conspicuous orange and yellow "shelves" on tree trunks, and it sometimes gets so big that a single specimen weighs tens of pounds.

This fungus causes wood to rot and weaken, and so it is a recycling agent in the forest ecosystem.

Around here, it has the reputation of being a delectable treat if collected when it is young and soft, and cooked well. So, on a recent hike, two friends collected a good handful, with the thought of a tasty dinner that evening.

And the dinner was indeed tasty.

Alas, however, the later consequences were seriously unpleasant with severe, even violent and prolonged gastric and intestinal disturbances.

Their experience differed markedly from that of three other friends, who also ate this fungus about the same time with no untoward consequences.

The difference between these consumers of the fungus caused us to do some searching on the Internet, which turned up interesting but incomplete information.

In the field guides and Internet sources, chicken of the woods goes by the scientific name of Laetiporus sulphureus, and it is recorded from many tree species including oaks, locusts, eucalypts, conifers and others.

However, recent studies have shown that there are really at least four or five separate species under this broad label in North America. These new species differ in their host plants, geographic ranges, chemical properties andgenetics.

The species reported to grow on conifers in the far Western U.S. is called Laetiporus conifericola (this may be the type we have locally, but that is not for sure since we found nothing specifically about Alaska).

All species of this fungus are pharmacologically active, with effects on blood functions and immune systems, and they have some antibacterial, antioxidant and anti-tumor properties, too.

Several references report that these fungi may take up toxins from the host tree (and almost all wild plants have some chemicals that help protect them against enemies). Specimens from eucalypts and locusts are reported to be noxious, either because of their own inherent biology, or because of substances absorbed from their host trees.

Several references note that specimens growing on conifers should be considered to be inedible. At least one reference states that Laetiporus huronensis, growing on eastern hemlock, has caused gastrointestinal upset in "many people." Whether or not this applies to the type growing on our western and mountain hemlocks is not clear.

Given that there are several closely related species of this fungus, and merely growing on different host trees may lead to chemical differences, it is not surprising, perhaps, that eating it can have different effects on different people.

On top of that variation, human physiology varies from person to person. Some folks may have allergic reactions after eating chicken of the woods. Consuming alcohol at the same meal is reported to increase the allergic reaction in some people.

This leaves us with the standard caution to would-be fungus eaters: try only tiny, well-cooked samples at first.

Chicken of the woods is not likely to be confused with any other fungus around here, so identification should not be a problem - unless we have more than one type. But remember that if you go elsewhere and collect what looks like the same fungus, it may be a different species with different chemical characteristics.

Much remains to be sorted out, but for myself, I think I'll leave the gaudy thing to grow on the trees and perform its ecosystem job.

• Mary F. Willson is a retired professor of ecology.

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