THE FUNGI 93 



but in many cases they seem to arise in a purely vege- 

 tative way without any formation of sexual organs. 



Many of the Ascomycetes show remarkable polymor- 

 phism, this being especially marked in the " Black- 

 fungi ' or Pyrenomycetes, of which the ergot of the 

 rye and the "black knot' of cherries and plums are 

 examples. In these there are, in addition to the asco- 

 spores, several different forms of conidia cut off from 

 the tips of the hyphse. 



THE BASIDIOMYCETES 



The Basidiomycetes include most of the more familiar 

 large fungi, known popularly as mushrooms, toadstools, 

 puff-balls, etc. These fungi have no very evident affin- 

 ity with the sac-fungi, and as yet none of them have 

 shown any traces of sexual reproduction. The great 

 majority are saprophytes, the mycelium or vegetative 

 filaments ramifying extensively through the substratum, 

 which usually is earth rich in decaying vegetation, rot- 

 ten wood, or similar dead organic matter. From this 

 mycelium the spore-fruit arises, apparently in all cases 

 as a purely vegetative growth. Most Basidiomycetes 

 produce but one kind of spores, borne upon club-shaped 

 cells known as basidia (Fig. 25, E), and it is still an 

 open question whether the spore-fruit in these can prop- 

 erly be compared to that of the Ascomycetes. 



The basidia are swollen, club-shaped cells, borne at 

 the end of hyphse, and from each basidium grow out 

 several, usually two or four, little protuberances, each 

 of which produces a single spore at the tip. These 

 basidia are usually formed upon special parts of the 



