VOL. I11.] Polyporoid Fungi. . 93 
To one who has made any considerable field study among the 
Polyporei their most striking peculiarity is extreme variability owing 
to habitat, state of growth, seasonable conditions and many other 
circumstances of environment. When Polyporus hirsutus, for in- 
stance, grows on the upper side of a log its pileus tends to produce 
a complete circle, thus reducing its attachment to a short central 
stem; when it grows on the side of a log its pileus has the normal 
semicircular form, but when it grows beneath the log it is reduced 
to a completely resupinate condition. And yet these forms re- 
present three of the five subgeneric sections of Polyporus as usually 
recognized! It is easy to see how closet botanists poring over some 
herbarium fragments of pore-fungi, pour forth new species and 
genera by the score. 
The connecting character of the family has long been noted. In 
1836 Fries writes: “ Prorsus intermedit inter Agaricinos et Hydneos'.’ 
Peck’ has given an extended discussion of the intermediate char- 
acter of the variable Dedalea confragosa showing its intimate rela- 
tions to the three genera, Polyporus, Trametes and Lenzites. Two 
other common species of Dzedalea possess also intermediate char- 
acters. LD. améigua is clearly in the form of its pores a species of 
Deedalia, but in its texture and other characters it is a species of 
Trametes with which indeed Fries had united it. JD. unicolor, es- 
pecially in its older stages, can scarcely be distinguished from an 
Irpex. Polyporus is also connected with Irpex through two variable 
and closely allied species, P. abzetinus and P. pergamenus. Indeed 
these species are so closely related in some of their forms that their 
chief difference consists in one uniformly growing on the wood of 
Coniferze and the other on the wood of deciduous trees! The lacerate 
pores of these species are often difficult to distinguish from the flat- 
tened teeth of Irpex.’ Polyporus is further related to Lenzites 
through a polyporoid form of Lenzites sepiaria which, taken apart 
from its evident connections, would form an excellent species of Poly- 
porus. : 
1Epicrisis, 408. 
230th Regents Report, 71. 
*Peck (42d Regents Report, 38), has described var. irpiciformis of P. abietinus 
and calls attention to a second form of this species, which has been described aS: 
(Urpex fuscoviolaceus). 
