BOLETI OF THE UNITED STATES. 8I 
Terrestrial, fleshy, putrescent, centrally stipitate fungz ; 
many of them valuable for their esculent qualities, a few 
potsonous. Hym. Eur. p. 495. 
This genus abounds in species and is related to Boletinus 
on one hand and to Polyporus on the other. From the 
latter it is distinguished by the absence of a trama and from 
both by the tubes being easily separable from the hymeno- 
phore and from each other. Some of the species are very 
variable, others are so closely allied that they appear almost 
to run together. 
Most of our Boleti, appear in the warmest part of the 
season and especially in very warm showery weather. They 
are scarce inadry time. In this latitude a few common 
species may be found from June to October, but most 
of them occur only during July and August. Some species, 
like B. edulis, B. eximius and B. felleus occasionally attain 
a very large size; others exhibit a singular change of color 
in their tubes or flesh where these have been wounded. 
The pileus is generally so fleshy that it is apt to be infested 
by the larve of insects, and that it is difficult to dry speci- 
mens so that they shall retain their size, shape and colors. 
The species are generally terrestrial, but B. hemzchrysus 
is habitually lignicolous, and others are occasionally so. 
The spores vary in color in such closely related species 
that this character is scarcely available for’ general classifi- 
cation, but it is valuable as a specific character and should 
always be noted. 
The color of the dry spores sometimes differs slightly 
from that of fresh ones, greenish tints often disappearing in 
old and dried spores. The color of the hymenium is often 
paler in the young plant than it isin the old one. Fries has 
divided the genus into two series depending on the color of 
the young hymenium, but this division sometimes widely 
separates species that are evidently closely related. It has 
not therefore been fully followed in the present arrange- 
ment. Some.of the Friesian tribes or sections also are so 
» 
