This section is from the book "Our Edible Toadstools and Mushrooms and How to Distinguish Them", by W. Hamilton Gibson. Also available from Amazon: Our Edible Toadstools And Mushrooms And How To Distinguish Them.
Alveolate Boletus - Boletus alveolatus
Pileus: Smooth, polished; bright, deep crimson or maroon, occasionally mottled or marbled with yellowish; three to six inches in diameter.
Flesh: Firm and solid in substance; pale greenish or yellowish white, changing blue in fracture or where bruised.
Tubes: Tube-surface reaching the stem proper; undulate with uneven hollows; maroon, the tubes in section being yellow beyond their dark red mouths.
Spores: Yellowish brown.
Stem: Usually disproportionately long, covered with depressions or oblong pitted indentations, with intermediate coarse network of raised ridges; red and yellow.
Habitat: Woods; quite common.
Bitter Boletus - Boletus felleus
Pileus: At first firm in substance, becoming soft and cushionlike; smooth, without polish, varying in color from pale ochre to yellowish or reddish brown; diameter three to nine inches.
Flesh: White on immediate section, generally changing to slight pinkish or flesh color in fracture.
Tubes: Tube-surface rounded upward as it reaches stem; white at first, becoming dull pinkish with age, or upon being bruised.
Spores: Flesh colored or dull pink.
Stem: Usually quite stout, nearly as smooth as the cap, and somewhat lighter in color; more or less ridged with coarse reticulations, occasionally covered with them to its thickened base.
Habitat: Rich woods and copses, often about decaying trunks.
Plate XXIV Boletus Alveolatus. Boletus Felleus.
The crimson Boletus