154 Minnesota Plant Diseases. 



ering the entire spore-bearing surface. Such palisades are 

 common in all of the mushroom allies, in most gelatinous 

 fungi, "Jews' ears/' etc. In many of the closed fruiting bodies, 

 e. g., puff balls and birds'-nests, internal chambers, which are 

 formed in the early stages of growth, are lined with such pal- 

 isades. The fruiting body may assume many shapes, which 

 apparently tend toward the increase in spore-bearing area or 

 have to do with advantages of distribution. 



The variety of forms is enormous ranging from such sim- 

 ple types as the club fungi and smooth shelves to the tooth, pore 

 and gill fungi, and from puff balls to carrion fungi. The teeth, 

 pores and gills are the basidium-bearing regions. In the puff-ball 

 allies, the birds' nest and carrion fungi, the spore-bearing region 

 is in a closed fruiting body which either opens only by decay 

 or at maturity by a special pore or other device. Inside of 

 these closed bodies the basidia may occur in palisades lining 

 the surfaces of chambers, or they may occur on wefted threads 

 in no regular arrangement. The details of the fruiting bodies 

 will be given under the various groups. In a comparatively 

 few forms accessory spore-forms are found but they are not 

 nearly so common in this series oi fungi as they are in the sac 

 fungi. The question of the occurrence of a breeding process 

 is still an open one. A fusion of elements in the young basid- 

 ium or in the winter spore of rusts is interpreted by many as 

 a breeding act, and recent investigation has shown that in the 

 rust winter-spore the fusion is the culmination of a breeding 

 act which begins in the cluster-cup stage. The stalked fungi 

 do not seem to show any striking similarities to either the 

 algal fungi or to the sac fungi, so that in the light of present 

 knowledge only an isolated position can be assigned to them. 

 Various theories have, however, been proposed uniting this 

 group with each of the other great fungus groups. The latest 

 investigations indicate a relationship with the red sea-weeds. 



Perhaps the majority of the stalked fungi are earth-inhabiting 

 or wood-inhabiting saprophytes. Many, however, as the rusts 

 and smuts, are highly specialized and destructive parasites, 

 while not a few, as pore and other shelf-fungi, are half-sa'pro- 

 phytes. The timber and timber-tree diseases are largely mem- 

 bers of this group and the rusts and smuts are without doubt 



