SAP-ROTS OK SPECIES OF DECIDUOUS TREES. 61 



losam occurs on practically all of the oaks, and probably on other 

 broadleaf species. It is sometimes found growing in wounds on liv- 

 ing trees, but is strictly confined to dead wood. It is widely dis- 

 tributed in the United States and is one of the chief fungi destroying 

 oak wood. 



SAP-ROT CAUSED BY DAEDALEA QUERCINA. 



One of the most important enemies of structural oaks (Quercus 

 spp.) and chestnut (Castanea d< ntl<i (Marsh.) Borkh.) is Daedalea 

 quercina (L.) Pers. Plate X shows an end view of a white-oak tie 

 with the sporophores of this fungus ; also a section of the same tie 2 

 feet from the end. This fungus has a world-wide distribution. It is 

 one of the most common forms on oak and chestnut logs, ties, tele- 

 graph poles, fence posts, bridge timbers, etc., all of which it destroys 

 with rapidity. The conditions favoring the spread of this fungus, 

 the manner in which the wood is infected, and the rate of growth are 

 in a general way very similar to those described for the two preceding 

 fungi. The sporophores form either singly or in groups. They are 

 sometimes found growing out from large wounds upon the sap wood 

 of standing trees; hence, this fungus has been frequently described 

 as one causing a disease of living trees. The sporophores are tough 

 and rigid, with a corky consistency. They are first white in color, 

 but gradually turn darker to a gray ; the upper surface is zonate ; the 

 pores are elongated and have a wavy outline. 



The wood decayed by this fungus is generally moist and mushy, 

 but on drying becomes harder, although when rubbed between the 

 fingers it crumbles into a fibrous mass. 



OTHER SAP-ROTTING FUNGI. 



In addition to the sap-rotting fungi referred to there are a large 

 number which grow more or less frequently on broadleaf species of 

 wood. Their number is so large that it is impossible to refer to all 

 of them here, and only a few of the more typical ones can be men- 

 tioned. Among these are the following: Polystictus Idrsutus Fr., P. 

 sanguineus (L.) Mey., P. dnnabarinus (Jacq.) Fr., Poria subacida 

 Peck., P. vaporaria Fr., Poli/porus betulinu-s (Bull.) Fr., P. gilvus 

 Schwein., P. adustus (Willd.) Fr., Lenzites corrugata Klotzsch, L. 

 vialis Peck., and L. betulina (L.) Fr. 



All of these forms and many others grow singly or, more frequently, 

 in masses on dead wood, which they destroy with varying degrees of 

 rapidity. The manner in which they enter the wood and the rate of 

 growth differ slightly for the different forms, but for practical pur- 

 poses they need not be distinguished from Polystictus versicolor and 

 P. pergamenus. Detailed studies of most of these forms are yet to 

 be made. Some of the forms which attack beech wood have recently 

 been described by Tuzson (103). 



149 



