oming soft in age. The color varies greatly, from buff to dull
reddish, to reddish-brown, tawny-brown, often yellowish over a portion
of the cap, usually paler on the margin. The flesh is white or tinged
with yellow, sometimes reddish under the cuticle. The =tubes= are white
when young and the mouths are closed (stuffed), the lower surface of the
tubes is convex from the margin of the cap to the stem, and depressed
around the stem, sometimes separating from the stem. While the tubes are
white when young, they become greenish or greenish-yellow, or entirely
yellow when mature. The =spores= when caught on paper are
greenish-yellow, or yellow. They are oblong to fusiform, 12--15 mu long.
The =stem= is stout, even, or much enlarged at the base so that it is
clavate. The surface usually shows prominent reticulations on mature
plants near the tubes, sometimes over the entire stem. This is well
shown in Fig. 164 from plants (No. 2886, C. U. herbarium) collected at
Ithaca, N. Y.

[Illustration: PLATE 57, FIGURE 165.--Cap light brown, tubes greenish
yellow or yellowish; stem in these specimens not reticulate (2/3 natural
size). Copyright.]

Figure 165 represents plants (No. 4134, C. U. herbarium) collected at
Blowing Rock, N. C., in September, 1899. The plant is widely distributed
and has long been prized as an esculent in Europe and America. When raw
the plant has an agreeable nutty taste, sometimes sweet. The caps are
sometimes sliced and dried for future use. It is usually recommended to
discard the stems and remove the tubes since the latter are apt to form
a slimy mass on cooking.

=Boletus felleus= Bull. =Bitter.=--This is known as the bitter boletus,
because of a bitter taste of the flesh. It usually grows on or near much
decayed logs or stumps of hemlock spruce. It is said to be easily
recognized by its bitter taste. I have found specimens of a plant which
seems to have all the characters of this one growing at the base of
hemlock spruce trees, except that the taste was not bitter. At Ithaca,
however, the plant occurs and the taste is bitter. It is one of the
large species of the genus, being from 8--12 cm. high, the cap 7--20 cm.
broad, and the stem 1--2.5 cm. in thickness.

The =pileus= is convex becoming nearly plane, firm, and in age soft,
smooth, the color varying from pale yellow to various shades of brown to
chestnut. The flesh is white, and where wounded often changes to a pink
color, but not always. The =tu