Boletes are fleshy terrestrial mushrooms that have sponge-like tubes, not gills, as most mushrooms have, under their caps. (Polypores also have tubes, but are tough and leathery and usually grow on wood.) Spores develop on basidia (club-shaped, spore-bearing structures) which line the inner surfaces of the tubes. Because the basidia are vertically arranged, the spores, when mature, drop down and disperse into the air.
The majority of bolete species are edible, but there are two reasons not to harvest them unless you are with an expert. One reason being that there are some poisonous bolete species. The second reason is that because they are large and fleshy, larvae can often be found inhabiting them, as well as parasites.
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