12 



BULLETIN '722, U. S. DEPARTMENT OF A(!HlCrLTURE. 



the year are comparatively short, so that the sporophores of peren- 

 nial fungi may never at any time be entirely dried out. During the 

 late fall, extending into December and coincident with the formation 

 of new fruiting surfaces of the Indian-paint fungus, rain falls almost 

 constantly. The average annual precipitation is between 20 and 30 

 inches, increasing rapidly with elevation, reaching a maximmn of 

 more than 40 inches in the higher slopes. 



In the spring of 1915 investigations were begun on the river- 

 bottom and slope sites of the Priest River valley in Idaho. The 

 general altitude of the region is about 2,450 to 2,500 feet. The 

 meanderings of the Priest River in former times created a number of 



Fig. 9.— Cross sections of a hemlock branch in which heart-rot extended 10 feet out from the trunk, showing 

 how the larger branches may be afTected. 



swamps and bayous, which are filled with water during the greater 

 part of the year. The interlying areas are poorly drained. 



The whole region is one of dense forests, composed of western wliite 

 pine (Pinus monticola), western red cedar (Thuja ylicata), western 

 larch (Larix occidentalis), Engelmann spruce (Picea engelmanni), 

 Douglas fir (Pseudotsuga taxifolia), western hemlock (Tsuga Tietero- 

 'pTiyTUi), grand fir {Ahies grandis), western yew (Taxus hrevifolia), 

 western birch {Betula occidentalis), and cottonwood {Po'pulus tricho- 

 car-pa). 



The soil is a moist sandy loam, with much alluvial material and 

 not well drained on the river-bottom sites. There is a great depth 

 of humus, litter, and needles. On the above-described site, ten 



