The caps are saffron coloured or yellowish-brown, though they can be a dark chestnut brown. As the mushroom ages, the cap flattens. The cap can be anywhere from 2 to 5 inches wide (5 to 13 cm.) Under the cap, there are pores instead of gills.
The stalk of the mushroom ranges from 1 to 3 inches tall (2.5 to 7.5 cm.)
The caps of Slippery Jacks are quite sticky. When they are wet, for instance after a rainfall, they become downright slimy. The sticky skin makes it a not highly sought after mushroom
The white flesh yellows as it matures, but it doesn’t change colour when cut (e.g. doesn’t react to air.) Consequently, some wild mushrooms advise peeling them as they are picked so that they don’t stick together. When the underside starts to turn from yellow to brown, though, the mushroom is getting very old.
Slippery Jacks have a spongy texture and a very mild, bland flavour. In fact, for most people, given the lack of aroma and taste and the unpleasant, fussy handling that is required (they must be peeled before using), Slipper Jacks aren’t worth the bother. Even Italians, who don’t mind going to extra work and care where food is concerned, say it’s not really worth it.
Dried mushrooms exported from China and South America labelled “Porcini” are often actually Slippery Jacks.
Best used in dishes rather than used on their own as a side or as a “featured” ingredient.
The slimy skin needs to be peeled off.
Don’t try just slicing them up and frying them, they will become a slimy goo. Cook whole, peeled.
The side benefit of peeling the skin off is that some people who have eaten the skin get a gippy tummy (gastrointestinal upset) afterwards and have to spend a while on the toilet.
Occasionally called “Butter Mushroom”, but this is not a reliable name to use as there are at least two other mushrooms called Butter Mushrooms, Pholiota aurivella and Tricholoma auratum (“Butterpilz”) in German).
Though one might think that such a viscous mushroom would be prized in Japanese cooking, as other viscous funguses and plants are, it’s not. In some areas of Japan, they won’t eat it, calling it the “Maguso” mushroom, “maguso” meaning horse shit. The more widespread name for it in Japan is “Numeri iguchi”, which means a “slimy boletus (mushroom)”.
Its many names in many languages are often the same as those used for Granulated Bolete Mushrooms, but that’s fine, as it is essentially the same as far as cooking and handling go.
Part of its scientific name, “luteus”, means “yellow”.