182 



Minnesota Plant Diseases. 



dust-like clouds or puffs and are caught by the wind and may 

 be transported considerable distances. The chambers with 

 their palisade lining are not seen in the mature fruiting body 

 and can only be observed when the latter is young. The inte- 

 rior is then fleshy, white and more or less solid, and with age 

 gradually gets yellowish-green and soft, and even semifluid, 

 finally producing the dust of spores in the thread weft. (Figs. 

 81 to 91, see also following seven groups.) 



FIG. 91. The same group as in Fig. 80, taken two weeks later; shows the opened puff-balls. 



Original. 



Long-stalked puff-balls (Tulostomaca?). One frequently 

 meets in sandy places and in open fields groups of small puff- 

 balls about one-half to three-fourths of an inch in diameter, 

 mounted on long stalks which in some cases attain a length of 

 six inches. At maturity the spores form a powdery dark brown 

 mass and are thrown out through a pore in the puff-ball wall. 

 The puff-ball is formed just under the surface of the ground and 

 is raised up above the ground by the somewhat rapid growth 

 and elongation of the stalk, so that the puff-ball is elevated to 

 an advantageous position for the scattering of spores. The 

 mycelium forms strands and the fungus is an earth-dwelling 

 saprophyte. (Figs. 3, 81, 92.) 



