Wild Profile: Meet the tinder conk mushroom

A tinder conk fungus growing on a beech tree By Giuma/Shutterstock

The tinder conk? Funny name, cool mushroom. Unlike some other varieties, which, in fall, pop up briefly all over cottage country—they sprout during rainy weather—the strange-looking tinder conk is a long-living polypore fungus. You’ve surely seen it before, clinging to the side of trees, stumps, and logs. The tinder conk looks a little like a horse’s hoof (hence its nickname, “hoof fungus”—ew). Not the prettiest of tree growths.

Is “fungus art” dangerous?

Tinder conks typically grow on hardwoods. The mushroom itself is the fruiting—a.k.a. visible—part of a “mycelial network” inside the tree. In late summer and fall, the mushroom grows in a downward direction, adding a new layer. Look carefully—this is why these fungi have a ringed appearance. They’re tough and woody, one of the reasons why they can last for 30 years, and grow until they’re up to 15 cm wide, getting more and more flared at the bottom every season. They grow well into winter, protected by a sort of natural antifreeze. During a thaw, when the temperature climbs to a few degrees above zero, one tinder conk can spit out 240 million spores every hour. All it takes is one spore to germinate on a broken tree branch, and a new mushroom is born.

While the outside of a conk is hard, the inside is fleshy. Split open and allowed to dry, shavings of the mushroom make for a good fire-starter—hence the name “tinder.”

Cottage Q&A: Harvesting chaga mushrooms

Feature Video