Minnesota Plant Diseases. 183 



Hard skinned puff-balls (Sclerodermatacece). Many of these 

 puff-balls form their fruiting bodies at least partially under- 

 ground. The coat is hard and leathery in texture and usually 

 opens by splitting in some irregular fashion. The spores also 

 form a powdery mass which in our common species is dark vio- 

 let in color. The fruiting bodies are usually large in size, at- 

 taining a diameter of five and six inches in many cases. In their 

 immature condition they are superficially not unlike potatoes 

 in appearance. These fungi are also earth-dwelling sapro- 

 phytes. 



FIG. 92. Stalked puff-balls (Tulostoma mammosum). The puff-balls have been raised 

 from the sandy ground on stalks just before the opening and shedding of spores. 

 Original. 



Sphere-throwing fungi (Sphaerobolacece). These are very 

 minute fungi and not easily recognized as puff-balls. The fruit- 

 ing body is usually not more than three-sixteenths or one- 

 eighth of an inch in diameter and covered with a soft whitish 

 outer coat. Inside of this is an elastic covering which, at the 

 maturity of the spores and after the outer coats have been 

 split, inverts and forcibly ejects the whole mass of spores. The 

 latter remain attached together in a solid sphere and never form 

 a powdery mass. The sphere may be thrown as far as six feet 



