Minnesota Plant Diseases. 



26: 



stumps and cut timber in a manner similar to tlie preceding- 

 species. 



The velvet-stemmed Collybia rot (Collybia velntipes Curt.). 

 This is an exceedingly abundant fungus especially on cut tim- 

 ber and standing stumps or fallen logs. The fruiting bodies are 

 of the gill-fungus type and usually occur in clusters. The upper 

 surface of the cap is yellowish to tawny and in wet weather is 

 viscid. The gills are light yellow to tawny and produce white 

 spores. The stem is covered with a velvet-Hke coat of a dark 

 brown to blackish color, especially toward the base of the stem. 

 The fruiting bodies are about one to three inches in length and 



Fic. 131. — Fruiting bodies of the sapid Pleurotus (Pkurotus sapidus), on a standing yellow- 

 birch trunk. Original. 



the cap about one to two inches across. They may be found 

 at almost all seasons from early spring to late fall. This fungus 

 causes one of the rots of timbers and is usually a saprophyte. 

 It has been observed on living elm trees, however, and is possi- 

 bly a wound-parasite. 



The elm Pleurotus rot (Pleurotus ulmarius Bull.). This very 

 common gill-fungus is usually found on elms and maple trees,, 

 growing from dead trunks or from wounds in the living trees. 



