West: Undescribed Timber Decay of Hemlock 263 



Mr. C. G. Lloyd has repeatedly stated in his writings that P. 

 tsugae is not a good species but only the coniferous wood form of 

 P. lucidus. A careful examination, however, shows differences^ 

 that are sufficient to warrant its being retained as a separate 

 species. First, the context in P. lucidus and P. curtisii is made 

 up of two layers, the upper one quite whitish and the lower hav- 

 ing brown hyphae running all through it, so that to the naked 

 eye it appears brown ; in P. tsugae on the other hand, the context 

 is never duplex and does not have the brown hyphae, so that the 

 context is light and concolorous from crust to tubes. The dif- 

 ference is very apparent when the pilei are cut vertically and 

 compared. The red varnishing of the pileus is also very char- 

 acteristic. In P. lucidus and especially in P. curtisii the red color 

 fades into yellowish brown in spots in almost every specimen, 

 such spots being of a dull color. In P. tsugae the pileus is of a 

 dark red or mahogany color all over, with a bright glossy sur- 

 face. This distinction holds good even in old herbarium speci- 

 mens if mature when collected. Under the microscope, the type 

 of the hyphae is a distinguishing character. In P. lucidus and 

 P. curtisii the hyphae are rather slender, being about 4-10 

 microns in diameter on the average. The hyphae in these two 

 species are not very abundantly branched though they cannot be 

 said to be unbranched by any means. In P. tsugae there are 

 slender hyphae but they are always abundantly branched. Be- 

 sides there are numerous short thick hyphal elements that may 

 be as high as 15 microns in diameter and of very various lengths. 

 These have many small branchlets coming off at various points 

 with many of these lateral hyphae branching several times and 

 terminating abruptly near by. This branching is very conspic- 

 uous under high power of the microscope where hardly a hypha 

 will cross the field without branching at least once, while in the 

 other two species, unbranched hyphae crossing the field of vision 

 were relatively frequent. The host may also serve as a guide to 

 the species since P. lucidus and P. curtisii are, as far as the 

 writer could find, always found on hardwoods, while P. tsugae is 

 confined to coniferous wood, especially hemlock. 



1 Ann. Mo. Bot. Gard., 2, 1915. Comp. Studies Polyporaceae. Overholts, 



