Minnesota Plant Diseases. 



179 



structure at the base of the stem or a ring-like fragment on the 

 upper part of the stem. The gills are then exposed to the 

 air and are ready to shed their spores. If the cap of such gill 

 fungi be cut ofif, placed on paper and kept thus in a closed 



- >mw!E-s»!- ~. - -"-'-•^ chamber, the spores will fall in 



, ., • ' such numbers as to give a very 



V^ ' distinct map of the gills. The 



spores are of various colors,, 

 white, pinkish salmon, ochre- 

 brown, dark-purple or black, 

 and this color difference has 

 been used as a basis for a 

 classification of the gill fungi. 

 In some dung-inhabiting 

 forms the gills liquify when 

 the spores are ripe and the 

 latter drip from the plant in 

 an inky fluid mass. Some 

 caps when broken exude 

 milky fluids of dififerent col- 

 ors : white, red or yellow. 

 Such are known as the milk 

 fungi. The great majority of 

 the gill fungi are true sapro- 

 phytes. Many are earth-in- 

 habiting or dung-inhabiting 

 and an enormous number are 

 wood-dwelling forms. These 

 contain many of the chief tim- 

 ber-rot fungi as well as many 

 wound-parasites. A few are 

 The gill fungi find their chief 

 economic importance, outside of their timber-rotting efifect, 

 and as agents in the decay of plant debris, in the food products 

 which they furnish to man. The commercial mushroom is a 

 member of this group and hundreds of wild forms are ed- 

 ible. The latter are being used more and more extensively as 

 food by those who take the pains to hunt them up and to know 

 them. There are likewise some fungi of this group which are 



Fig. 88. — The shaggy-mane fungus. This 

 fruiting body is in a more advanced 

 stage of deliquescence, than that shown 

 in Fig. 87; almost the entire cap has 

 dripped off. A ring (annulus') is seen 

 at the base of the stalk. Original. 



parasitic on other gill fungi. 



