30 THE "bluing" and THE ''RED ROT'' OF THE PINE. 



standing- trees thej^ occur onl}' at the base of the trees (PL XllI). 

 Here thev g-row close to the ground and oftentimes their lower surfaces 

 are actuall}' in the ground. Grass, pine needles, and stones almost hide 

 the entire sporophore. 



Older punks are- rough on top and appear to be covered with some 

 waxy substance which has hardened and cracked. This substance, 

 when scraped, resembles a hard resin. It is brittle, and is readily 

 soluble in alcohol and xylol. It has a sticky appearance, and when 

 f reshh' formed on the younger parts its bright red color forms a distin- 

 guishing character not readily overlooked. The younger parts are 

 sometimes flesh color, then again reddish yellow in color, and as they 

 grow older the}^ turn more decidedly red. The surface is at first 

 smooth and wax}-, and as the sporophore grows older it becomes very 

 much wrinkled. The outer waxy covering cracks (PI. XIII, fig. 2), 

 and the whole surface then seems to be coated with a dull gray, lime- 

 like substance, which is exceedingly characteristic. 



The red-rot fungus belongs to the Hymenomycetes, genus Polyporus 

 {Fomes), and differs decidedlv from other species of this genus. The 

 species most closely related to it are PoJyporim pinicola viiW^ Polyporus 

 marginatus. Its whole appearance, its color, hard resinous covering, 

 and very rough surface distinguish it from these species. It has been 

 decided to consider it as a new species — -PoJyjJorus p)07iderosus, u. sp. — 

 which may be described as follows: 



A large Polyporus of the Fomes type usually growing singly (PI. XI, fig. 2), some- 

 times two or three together (PI. XIII, fig. 2), broadly applanate; about as thick in 

 the back as it is wide (PI. YII, figs. 10 and 11) ; top, when young, fliesh-colored to 

 yellow red, becoming darker red with age; smooth when young, rapidly becoming 

 rough and covered with irregular nodules. Older specimens show numerous ridges, 

 formed by regular additions (annual) on the edge and below. Top covered after 

 the first year with a hard, brittle, dull, resinous substance, which cracks as it grows 

 old, and looks sandy or crystalline. Lower surface smooth, pores very regular, 

 almost round, extending out to a line which is about one-fourth inch in width. ( See 

 PI. YII, figs. 10 and 11.) Common on dead trees and fallen logs of the western 

 yellow or bull pine {Pinus ponderosa) in South Dakota. 



RATE OF GROWTH OF " RED ROT." 



The question as to the rate of growth of the "red rot " is one of great 

 practical significance. The "red rot"" fungus is the principal cause 

 which prevents the dead wood from lasting indefinitely.' It usually 

 attacks the trees when they have reached the "black-top'' stage; i. e., 

 toward the end of the second year after the beetle attack, and there- 

 after. The larger number of trees are probabh' free from this rot 

 until the third year. To make this clearer, one may make a schedule 

 of the stages through which the trees go, about as follows: 



