[4] According to Murrill's definition of the genus, species of Boletellus have an annual fruit body that grows on wood and a stem that is centrally placed.

[3] Additional characteristics of the genus have been delineated or amended since its original description over 100 years ago: spores have longitudinal ridges or "wings", are inamyloid, and rarely dextrinoid (staining deep reddish to reddish brown in Melzer's reagent).

Species usually have hymenial cystidia present, and clamp connections are typically absent (with the exception of B. fibuliger).

[3] Singer's fourth edition (1986) of his Agaricales in Modern Taxonomy included 33 species, which were classified into sections depending on moisture content, scaliness of the cap or amount of ornamentation on the stem.

[4] In general, Boletes usually have smooth spores, but Boletellus, Austroboletus, Strobilomyces, and Heimioporus are exceptions to this.