Sorry, it's a Suillus (by )

Mushroom of the Month: May, 2016

Suillus luteus One of the most common remarks I get from eager beginners in the fall and winter is, "look at all these Boletes!" Excited that they have just hit the mother load of culinary excellence, I remark (as many before me), "sorry… it's a Suillus". As what a Suillus is and why it is not on par with a "true" Bolete is explained, you can see the disappointment set in. Just one of those mushroom "rights of passage" we all have to go through. You spend an hour in the woods collecting what you think is going to be the meal of the year, only to find out you have the culinary equivalent of a wet sponge, and a maggot riddled one at that! With a little time and experience however Suillus is one of our easier local fungi to ID at the genus level simply by sight.

Suillus in generic terms is a Bolete, a common reference for pored terrestrial mushrooms in our area. In scientific terms they are in the order Boletales, defacto making them a Bolete. However Suillus is not only in a different genus, they are now in their own family Suillaceae. So what do they have in common with the mushrooms in the genus Boletus that trip people up? A few things: overall stature, pores instead of gills, habitat, color (sort of) and wishful thinking… When you see literally 20lbs of light-brown capped, pored mushrooms poking through the duff in a stand of pines the mushroom fever kicks in, and what in actuality is Suillus pungens, for a few frenzied moments is the greatest haul of Boletus edulis ever. Someone once said if you listen closely you can actually here the mushrooms laughing at you…

So what makes a Suillus a Suillus and not a Boletus, Leccinum, Aureoboletus, Buchwaldoboletus, Suillus pseudobrevipes  by Christian Schwarz Chalciporus, Tylopilus, Xerocomellus or Xerocomus??? Lots of things, but here are a few stand-out macro characteristics that can be applied quickly in the field. First off, commonness and sheer quantity. Suillus out numbers Boletus by what at times seems to be a billion to one. That epic patch you just stumbled on is not Boletus, its Suillus. If it seemed too good to be true, that is because it is. The mushroom world plays by those rules as well. Also, Suillus will fruit fall through spring, whereas the prized edible Boletes tend to in fall and early winter, and normally only for a few weeks at best. Next is the slime! With the exception of one species in Aureoboletus none of the "Boletes" even remotely come close to the cap slime, stickiness or goo of Suillus. Those pesky glandular dots! These always confuse people, so the simplest description I can give is small, dark dots or blotches on the stem that are greasy to the touch. None of the other Boletes have these (scabers on Leccinum are more bumpy and hard). Another characteristic I go with is smell. Suillus tends to have a very fresh, almost fruity aroma. It is very pleasant and reminds people of frozen orange juice or coniferous trees. And finally the "close, but not enough" characteristics of size and color. Suillus can be big mushrooms, but Boletus are normally bigger. Suillus caps tend to be brownish, but not as brown or brick red as Boletus caps. Suillus have pores, but they are not quite like Boletus. Really after an exhaustive survey of both genera one sees there is little in common when observed at a more objective, granular level. Here is a "scientific" description we have put together for those that need a bit more:

Suillus is a large and cosmopolitan genus, present throughout the world (in some places due to introduction). Recognition of the genus can take some time (since they are quite variable and intergrade to some degree with other bolete genera). The fruitbodies are usually medium-sized boletes. The caps are variably colored and show many different textures (smooth and extremely viscid to dry and scaly or hairy), but most have an easily-peeled skin (unlike many other boletes). The pores are often angular or slightly irregular and sometimes radially-arranged. Inspection of the stipe is important, as almost all species show either a partial veil or greasy glandular dots (the latter trait is unique to the genus).

All are mycorrhizal, occurring in almost any setting as long as there are coniferous hosts in the family Pinaceae present. In our county, these hosts are the true pines and Douglas-fir.

The genus is fairly speciose in California, with diversity structured around host and habitat specialization. Many species likely are undescribed or go by misapplied names. Fruitbodies found under non-native pines should be compared directly against European references, a number of Eurasian Suillus have been recorded in other parts of the state.

All jokes and remarks aside, what about actually eating them? I have read in Europe they are regularly eaten and in some areas, mainly Slavic countries, they are a prized edible. Locally they are typically shunned in favor of the "real" Boletes, chanterelles, Amanitas, etc. I have eaten a few of the local species and admittedly they were not that bad. Only fresh, firm buttons were used and the cap skin and slime was pealed off. If you can, remove the pores as well. They were fried in light butter and salt and eaten by themselves. One time they were added to a basic soup. Suillus pungens in my opinion is the best tasting one, but as fate would have it is also the most slimy one! S. pseudobrevipes was not too shabby and both S. caerulescens and S. fuscotomentosus were palatable. Since during our mushroom season you are literally almost guaranteed to find Suillus at any given time, it is worth giving them a shot as an edible. If you like them you will never be out of mushrooms again!

Suillus actually are an interesting fungi to study as they have a very strict preference for mychorhizal hosts and apparently have very strict parasitic companions as well. Years of field work are showing that fungi in the family Gomphidiaceae parasitize Suillus on an intimate level. If research is correct literally each species of Suillus lives with only one type of conifer and is in turn parasitized by a specific species in Gomphidiaceae! That is pretty specialized stuff! If you pay attention in our local woods you can witness this behavior for yourself. But alas, this is knowledge just for the science geeks amongst us, and at the end of the day for the average forager Suillus will remain the mushroom world's consolation prize in the sweepstakes for Boletes.