84 



Minnesota Plant Life. 



There must l)e at least a thousand difterent kinds of leaf-spot 

 fungi growing- in Minnesota. Not all leaf-spot fungi are cer- 

 tainly black fungi ; l)ut the great majority of them belong to 

 that group. Neither do all leaf-spot fungi develop fruit-bodies, 

 for some of them are able to form only a simpler sort of spore- 

 cluster. Yet in most instances it is believed that this is because 

 the fungus has abandoned for some reason the formation of 

 true fruit-bodies. As already observed in the account of the 

 wheat rust — a most instructive object of study — a fungus may 

 ac(|uirc the habit of developing one kind of frtiit-l)ody upon 

 one leaf and another kind upon another. It is very probable. 



Fk;. 30. Fungus spot-disease of strawberrj' leaf. After Hailey. Hull. 79, Coruell I'uiv. Ag. 



Expt. Station. 



v/here leaf-spot ftuigi fail to develop their ordinary fruit-bod- 

 ies and ])r()\ide tliemselves with spore clusters, that they 

 may on other plants develop the true fruit-bodies, or that 

 they have, as is often prol)able, ceased altogether to produce 

 them. 



Not only do these spot-fungi find pasture upon the tissues 

 of living leaves but closely related forms browse upon old pieces 

 of paper, upon straw, leather, decaying cloth, the shells of nuts 

 and seeds, and e\cn upon such curious fields as the inner siu'- 

 face of roasted chestnuts, the feathers of fowls, the hair and 

 hoofs of cattle, and, in short, wherever the)' can find food-ma- 

 terials .siiilable for their Lirowth. 



