VOL. III.] Polyporotd 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 usuallv 

 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 

 1 836 Fries writes : " Prorsus intermedii inter A^aricinos et Hydneos^! ' 

 Peck' has given an extended discussion of the intermediate char- 

 acter of the variable DcBdalea con/ragosa showing its intimate rela- 

 tions to the three genera, Polyporus, Trametes and Lenzites. Two 

 other common species of Daedalea possess also intermediate char- 

 acters. D. ambigua is clearly in the form of its pores a species of 

 Daedalia, but in its texture and other characters it is a species of 

 Trametes with which indeed Fries had united it. D. tniicolor, 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. abietinus 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 

 Coniferse 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. 



' Epicrisis, 40S. 



*30th Regents Report, 71. 



^Peck (42d Regents Report, 38), has clescrilied var. irpiciformis of P. abietinus 

 and calls attention to a second form of this species, which has been described as 

 ( Irpex fuscoviolacens') . 



