Telluride Mushroom Festival pt3: the King Bolete

So for my 3rd micro-post about the mushrooms we found at the Telluride Mushroom Festival: our first-ever King Bolete, aka: Boletus rubriceps.

B. rubriceps was once thought to be B. edulis, which you may have heard of as the Porcini. It's also known as the Cep (France) or the pennybun (United Kingdom). However, DNA studies have shown that B. edulis is native only to Europe. Boletus rubriceps is a close relative, however, and considered to be part of the Boletus edulis "complex".

My husband found the only king bolete of the trip, we were at or around 10,500 ft, up on the side of Lizard Head. The foray lead told us that Amanita muscaria is frequently found nearby, and that its generally easier to find the red A. muscaria then it is to find the brown B. rubriceps, so to look for those, then look around.  (A muscaria is the bright red mushroom with the red spots that everyone thinks of when they think of a mushroom). Sure enough, he found the boletus within a few yards of where others were picking A. muscaria.

Without magnification, a young pore surface can resemble a spongy texture.

Like (almost) all Boletes, B. rubriceps has a cap and a stalk, with pores under the cap, instead of gills. It can be argued that there are no lethal North American boletes, though William David Fisher reported a red-pored bolete that was implicated in the death of a man with pre-existing health problems. In general, it's best to avoid the boletes that have red, orange or pink pore surfaces (the underside of the cap) and boletes that turn blue when you cut or handle them -- at least until you know what you are doing.

Ours was a little nibbled on by some animal, but not buggy.
We trimmed around where the animal had munched.

Boletes in the edulis complex have brown or reddish brown caps, white or cream pore surfaces, thick stalks, don't bruise blue or red, and have a light colored "reticulation" on the stem, near where it attaches to the underside of the cap. Reticulation looks like a netting, but is part of the mushroom surface.

White reticulation is a key identifying feature of the King Bolete, Boletus rubriceps.

The reticulation on edulis boletes will be hard to see, especially when the mushroom is fresh, as they must be white -- and the stem itself is white or cream. As the mushroom ages it becomes a bit darker, more of a beige or buff color. Dark reticulation is a sign of the bitter bolete, Tylopilus felleus, which won't make you sick, but is apparently so bitter that a single mushroom can ruin an entire dish.

More worrisome is no reticulation at all, which could be B. huronensis, the false king bolete, which can make you very sick. Boletus huronensis technically stains blue, but unlike most blue-stainers, the color will fade on the false king, and if you don't catch it, you might not know you have a poisonous mushroom.  I don't think B. huronensis grows in Colorado though, but I'm not sure.

I found B. huronensis once, in New York. I noticed that it lacked the white reticulation of the king, but when it didn't turn blue on handling and cutting I thought maybe I had a chestnut bolete, or something similarly safe. I was going to spore print it when I got home, but as chance would have it, I pulled it out of my bag to show someone, and the cap had turned blue where I cut it to check for bugs!

Now, unlike the brick-cap bolete (Boletus subvelutipes and friends), this wasn't a dark blue. It was sort of a pale sky blue. More importantly, about 10 minutes had past since I cut the fungi. And perhaps most confusingly, the blue staining faded right before my eyes. It had probably only been visible for a minute or two total.

The bottom line is that when harvesting mushrooms like these, at least in the Northeast, you definitely want to look for the white reticulation. If you don't find it, you know you don't have a King Bolete. At that point I would definitely recommend a spore print, and if your print comes back olive-brown, avoid eating it!

Special note: this is not a complete identification post,
as I never share identification until I have successfully identified and eaten a mushroom several times. This post is only meant to share an experience.