384 



DISEASES OF CULTIVATED PLANTS 



independent fungus and called Ptychogaster aurautiacus. 

 These structures resemble in general appearance young spore- 

 producing plants, and bear conidia in receptacles in the 

 flesh, but do not form tubes bearing true spores. 



FIG. 119. Polyporus sulfureus. Block of white spruce wood 

 showing injury caused by this fungus. (After Schrenk.) 



Polypoms squamosus (Fries.). This very common fungus 

 occurs abundantly on dead trunks and stumps of many kinds 

 of trees exclusive of conifers, and is also equally common 

 on old decaying trees, which it probably has in some measure 

 been instrumental in destroying, but so far there is no 

 reliable evidence to this effect. 



Usually imbricated or several pilei from one point. Pilei 

 on a more or less lateral stem, fan-shaped or nearly circular, 

 fleshy behind, and becoming thin towards the margin, dingy 



