Members of the order Boletales (commonly referred to as Boletes) are mushrooms characterized by holding their spores in small pores on the underside of the mushroom, instead of gills (as are found in agarics). Nearly as widely distributed as agarics, they include the king bolete, much sought after by mushroom hunters. The order Boletales has about 70 species (0,4% of the described homobasidiomycetes).
Similar to boletes, and generally only distinguished technically, are polypores.
Boletes are a relatively safe group of mushrooms for human consumption (none are known to be deadly to adults), provided that one:
Eats only young specimens
Avoids mushrooms with red or orange pore surfaces
Avoids those that stain or bruise blue to green (a common trait)
Avoids all Leccinium species with an orange cap
Two of the best common edible boletus however are bay boletus, whose gills bruise blue_green, and orange birch boletus, which is a Leccinum (not Leccinium) with an orange cap and which bruises a bluish grey (but which should not be eaten raw)
Note that to be safe, a positive identification should always still be made before consumption. Additionally, just because something is edible doesn't mean that it should be eaten, or will taste good at all.
Their caps look like the caps of the GilledMushrooms (a group that decided to hang seeds from sheets of cardboard, instead)--but, on the underside of the cap, there are tubes instead of gills.
Boletes are mycorrhizal partners with trees--so noting what kind of tree is "hosting" your bolete can also be important information in the identification process.
Some truly delicious edible mushrooms are among the boletes, as well as many that are "edible" but not particularly good, and a few that are poisonous.
Boletes are harvested all over the world, although they are not a good choice for inexperienced mushroom hunters, as proper identification can be tricky.
Boletes are quite fragile, usually emerging the day after a rain, and becoming soggy and insect infested shortly thereafter.
The most popular edible bolete is Boletus edulis, known in the United States as the King Bolete, in Italy as the Porcini, and as Steinpilz in Germany.