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Dannyís DNA Discoveries Ė Russula

by Danny Miller



Ben Woo was one of PSMSí founders and first president. He spent his life collecting more than 1,000 Russulas around the PNW from 1974 to 2007, drying and preserving them as well as taking great notes about each one of them. It is one of the best amateur collections of mushrooms ever made in the US. In 2014, the Stuntz Foundation generously paid to sequence all of Benís Russulas, the data from which was analyzed by Anna Bazzicalupo as part of her PhD dissertation at the University of British Columbia. This dissertation is easily the single largest contribution to local PNW Russula knowledge. When Anna sequenced them, we got a great idea of what many of our local species were. Of the 72 or so species she found in Benís collections, about 40 of them could not be named reliably and may represent new species, some unique to our area. I contributed to a paper she wrote describing nine new Russula species from the PNW and chose the name Russula benwooii to honour Benís lifetime of service to the club and society for what I thought was the most interesting Russula, described under the "Other Russulas" section of the Crown clade. Since then I have spent hundreds of hours further analyzing the data created by this Stuntz Foundation grant and here in this article I report on a number of fascinating revelations and discoveries.

Russula (and Lactarius) are two very interesting kinds of gilled mushrooms. First of all, even though they look like other gilled mushrooms, they are only distantly related yet evolved to look the same. If you study them more than superficially, though, you will quickly see that they are not at all like other gilled mushrooms, no matter how much they seem to be at first.

A quick look under a microscope at any Russula will tell you that they are unique in the mushroom kingdom. Most gilled mushrooms have smooth elliptical spores and many of the things you see surrounding the spores are long, stringy fibers, giving mushrooms their characteristic fibrous appearance:

ďRegularĒ gilled mushroom tissue © Danny Miller

Russula spores are almost spherical, and they have warts that turn black in iodine, something that doesnít happen too often with other gilled mushrooms. Also, many of the things you see surrounding the spores are other circular shaped cells.

Russula mushroom tissue © Danny Miller

Quite different, arenít they? All of those spherical cells give Russula and Lactarius the ability to break in any direction (the stems famously snap audibly like a piece of chalk when fresh) so if you find a dense, tasty species they will have the texture of celery, not the usual rubbery texture of other mushrooms. They can make great edibles, with a texture unlike any other mushroom, definitely one of the prizes for wild mushroom hunters that you just canít get in any store, at least around here.

Lactarius are probably appreciated more than Russula, because they bleed milk when broken, sometimes red, orange or blue milk! And one of them is the candy cap, the famous dessert mushroom. But Russulas donít do anything that cool. Most Russulas look very similar to each other and you can fairly quickly learn how to identify one: they all have the same somewhat squat stature. They are mostly white except for possibly a thin cuticle of coloured skin on the cap that can somewhat be peeled off, and perhaps another splash of colour will appear somewhere else, like a shade of yellow in the gills or a hint of wine colour in the stem. Many Russulas (and Lactarius) taste acrid or hot like a hot pepper and can burn your mouth! They form mycorrhizal (symbiotic) relationships with and are found on the ground near trees, almost never on wood nor far away from trees. The gill attachment is usually adnate (running straight into the stem).

Russulas are pretty easy to learn to recognize as a group, but exceedingly difficult to identify to species. Four of these nine photos may be the same species, R. sierrensis (photos 5-8)! © Ben Woo

But while you can easily learn to spot a Russula, knowing which species it is can be one of the most challenging identification puzzles. We probably have almost 100 species in the PNW and many of them look the same. Not only that, the same species might come in four or five different colours, so identical looking specimens could be different species and different looking specimens might be the same species. Many of them have not been described yet and have no name, so there is no Russula book you can look at to help you identify your local PNW Russulas. (Although we are trying to fix that. I am a co-author of the free MatchMaker program for MAC and PC, found at, which has the most up-to-date information about all our local species. I am also the author of a pictorial key to our local mushrooms, which is a part of MatchMaker but can also be found separately at and used on phones and tablets. This is so far the only place to get comprehensive information on local Russulas). This document is intended to represent the latest and most up-to-date information on local PNW Russula species.

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