Ahh, porcini mushrooms. How I do dote on thee. The name “porcini” applies to a cluster of mushroom species in the Boletus genus, and they are all edible and quite delicious. I have a penchant for adding porcini powder to almost anything that requires a little bit of oomph and umami (savory/delicious), because the flavor of these mushrooms is earthy, nutty, and at times a little smoky. Overall, porcini is not even CLOSE to my favorite mushroom; that esteemed distinction is reserved for the likes of morels, black trumpets, and hedgehog mushrooms.

Characteristics of Porcini Mushrooms

Porcini are complex and delicate culinary beasts, and well worth working with in the kitchen. I have written a post that goes through some of the ways in which porcini should be cooked and prepared, along with a few hunting tips, and in this post I will detail some of the mysterious and unusual things that make these mushrooms so unique in the world of humble fungi.
Porcini mushrooms are large and handsome mushrooms with a cap and stem. The underside of their caps is not gilled. Instead, they have an array of spongy tubes on the bottom of the cap. When the mushroom is young, the sponge is firm and white, and as the mushroom matures, the sponge starts to soften and turn yellowish. Over the course of a few days, the porcini expel spores from these spongy tubes.
In addition to the sponge, porcini have a few characteristics that aid mushroom hunters in identifying them; namely, they tend to have wide, thick stems that are at times just as broad (or broader) as the cap of the mushroom itself. The cap of the mushrooms range from a roasty, hazlenut brown to a dull red, depending on what sort of porcini they are, and what kind of forest they were found in. The caps of porcini, as with other mushrooms, can take on the color of leaf litter and other organic debris that they arise from, so if they are growing under a tree that is shedding red and brown leaves, this will sometimes stain the caps. Another common occurrence that causes porcini mushrooms to be off-color is that a leaf will land on the emerging mushroom, leaving  a spot on the cap that is less vibrantly colored than the remainder of the mushroom.

Another feature of porcini mushrooms is what mycologists call “reticulation” at the top of the stem. In the case of porcini, reticulation appears as a fine network of webbed brown coloration at the top of the stem that is mildly textured (see photo below). It kind of looks like stretch marks in many cases, in that as you descend down the porcini’s fat, thick stem, the webbing of the reticulation becomes wider.

Edibility Notes on Boletus Mushrooms

Porcini and other mushrooms in the genus Boletus are largely safe to eat, with exceptions. There are some boletes with red pores (the spongy bit referenced above) that cause mushroom poisoning and are toxic, especially Boletus satanus (Satan’s bolete) and Boletus pulcherrimus. Although red-pored Boletus mushrooms are gorgeous and rank among my favorite mushrooms from an aesthetic perspective, they are best left alone and have been linked to gastric infarcations.
Less concerning but still worth noting, there are a numerous Boletus mushrooms that stain blue when they are handled, cut, or bruised, and a couple of them cause sickness if you eat them. If you find a blue-staining bolete and you are not entirely sure what it is, it’s best not to try eating it, just to be on the safe side. The blue-staining action in Boletus mushrooms varies a great deal; some of them oxidize extremely quickly, and you can see the blue spread to every corner of a cut mushroom in a matter of a second or two. Some of them stain much more slowly, but they usually show any possible staining within 15 minutes.

Another cautionary note: there is a genus that is closely related to Boletus called Leccinum, or the scaber-stalks. Leccinum mushrooms have scurfy, often colorful scabers (or shreds of hairy material) on their stalks. Although many Leccinums are safe to eat, there are reports of poisoning being linked to at least one species of them.
Finally some pink-spored bolete-type mushrooms in the genus Tylopilus are quite bitter and purportedly cause a stomach aches (although are not otherwise considered toxic per se). Tylopilus mushrooms usually have a whitish sponge that turns pink or lilac as they mature, and they are so bitter it’s almost impossible not to spit it out at once. There are some Tylopilus mushrooms that aren’t bitter and can be consumed (Tylopilus indecisus being one), but if you get your hands on a bitter one and carefully chew a piece of the cap to test its flavor, you’ll know at once that you’ve got an inedible mushroom on your hands.
If you want to sample wild boletes, there are four decent rules that mushroom foragers often use:

1. No boletes with red pores
2. No boletes that stain blue (even slightly) when cut, bruised, or handled
3. No boletes with scabers (tufts of hairy material) on the stalk
4. No boletes that taste bitter when a small piece of the cap is chewed and spit out

Personally, these guidelines are not enough to make me comfortable; I opted instead to learn a few edible and choice boletes and learn them well, and stick with them. The tastiest Boletus mushrooms I will eat are Zeller’s Bolete (Boletus zellerii), the Spring King Bolete (Boletus Rex-veris), The King Bolete/Porcini (Boletus edulis), the Admirable Bolete (Boletus mirabilis), the Butter Bolete (Butyriboletus regius, formerly simply Boletus regius), and the Queen Bolete (Boletus aureus). I also eat some bolete-type mushrooms in the genera Suillus and Tylopilus and enjoy them a great deal.

Common Names for Porcini Mushrooms

Porcini mushrooms have a devout following in European countries, and as such there are many different common names for them. The word “porcini” is Italian, meaning “porcine,” which means of or relating to piggies. It is possible that the association between these mushrooms and pigs is observational: pigs do really fancy porcini mushrooms and will gobble them up without a second thought. Another popular theory is that baby porcini mushrooms look like piglets. This is sort of true, if you substitute a piglet head for a mushroom cap and subtract the legs and trotters. Anyway, it’s a bit of a stretch in my mind, but there you have it.

In Germany, porcini are known as Steinpilz, which means “stone mushroom,” perhaps because they can look rather like rocks when they are first emerging from the duff and debris on the forest floor. Another common name for porcini is Ceps, derived from French (who call them Cepes de Bordeaux) and Catalan.
By far my favorite common name for porcini is Dutch: Eekhoorntjesbrood, which means “squirrel’s bread.” This resonates with me because I have had to compete more fiercely with squirrels for boletes than any other sylvan creature; they’re really nuts for them (no pun intended).
One day, I was hunting boletes in the Sierra Nevada, and came upon a rather large patch of porcini that had been uprooted and scattered about. I decided to investigate and found some rather good specimens for my own basket nonetheless. As I crouched and started to gather together my mushrooms, I felt something splat/squish onto my head.
Revulsed, I tentatively put my hand up there and retrieved a small gob of porcini tubes stuck in my hair. Then I heard the noise: the miniature machine-gun chattering of an angry squirrel. I looked up and there he was, perched on a tree branch, a bit of porcini mushroom clutched in his paws, and what I imagined was a menacing expression on his face. Fortunately for me, he must have decided he wanted his mushroom more than he wanted me to to suffer further indignity, because he simply continued to harangue me verbally as I hurriedly finished collecting what porcini I could. To this day, I am mindful of the fact that I am not the only one who feels entitled to porcini mushrooms, and I always look out for squirrels when I find a patch of them in the woods.

The Multitudes of “Porcini” Mushrooms Be Not Known To Man

Even though porcini mushrooms are a commercial commodity, there are several different mushroom species that are sold as under that name. It is quite likely that when you purchase porcini in the market, you are actually getting a hodge-podge of different Boletus mushrooms that share the flavor, aroma, and appearance of true “porcini.” A particularly telling example of this was when a pair of scientists from the UK decided to do genetic testing on some Chinese porcini mushrooms that they bought at the store. The scientists, Bryn Dentinger and Laura Suz of the Royal Botanic Gardens, tested 15 different pieces of “porcini” in a package of dried Chinese mushrooms. Lo and behold, they discovered three new, unnamed species of mushrooms in the package.
This astonishing example of fungal diversity is not terribly surprising to me, but it does illustrate a good point: porcini, as with many mushrooms, have complex genetic roots and it is very difficult to say what a mushroom is, definitively and without question, without having access to DNA sequencing equipment (or at the very least some up-to-date books, a microscope, and some help from other mycophiles). But that doesn’t stop me from trying, and it shouldn’t stop you, either.