Rare, Expensive Japanese Mushroom Grows in Sweden

GOTEHNBURG, SwedenThe hon-shimeji mushroom, a rare and expensive Japanese gourmet delicacy costing up to SEK 8,000 a kilo, has been discovered growing wild in Sweden by researchers at the University of Gothenburg.

Lyophyllum is a family of many different species of fungi. One of them is Lyophyllum shimeji, previously believed to grow only in the Far East. In Japan, the hon-shimejior true shimejiis a delicacy.

We were visited by a Japanese mycologist who found a fungus on a pine heath outside Skellefteå which she thought was similar to hon-shimeji, said Henrik Sundberg, a student at the Department of Plant and Environmental Sciences at the University of Gothenburg. Using molecular techniques, weve now been able to show that this northern Swedish fungus is identical to the Japanese one.

This is not the first time that a Japanese gourmet mushroom has been found in northern Scandinavia. Just over a decade ago, researchers were able to show that the Swedish mushroom Tricholoma nauseosum was identical to the Japanese species Tricholoma matsutake. Interest in the Swedish matsutake has been huge, and Japanese mycologists and traders have made their way to the countrys northern forests to study the fungus.

It was also the Swedish matsutake that led Japanese mycologist Etsuko Harada to the forest outside Skellefteå where she found the Swedish hon-shimeji in August 2008.

After getting a positive response from Japanese mycologists, we became more and more convinced that we were on the trail of a Japanese delicacy, Sundberg said. When we found more the following year, we started up a project to examine the fungus using molecular techniques. We were soon able to show that the Swedish and Japanese fungi are, without a doubt, identical.

So far the Japanese fungus has been found on sparse pine heaths and flat-rock forests from Umeå to Gällivare in northern Sweden, as well as in Dalarna in the middle of the country. The reason why it did not previously attract attention is partly that it was lumped together with related species, and partly that nobody made the link with hon-shimeji. Finds in Norway and Finland suggest that the fungus is probably found throughout the taiga belt of boreal forest from Scandinavia to China and Japan, and maybe even in other areas with a temperate climate and pine forests, such as Scotland, Canada, the United States and Central Europe.

The Swedish hon-shimeji probably forms fruiting bodies from August through to the first frosts. It is similar in appearance to its closest relatives, Lyophyllum fumosum and Lyophyllum decastes, but does not grow in such big clusters and often has a thicker stem which swells toward the base and sparser gills.