TAXONOMY 



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ruptures, are discharged and are carried by the wind to other fields 

 of grain, there to begin over a new life cycle. 



CLASS III. BASIDIOMYCETES, OR BASIDIA FUNGI 



This large class of fungi, including the smuts, rusts, mushrooms, 

 gill and tooth fungi, etc., is characterized by the occurrence of a 

 basidium in the life history. A basidium is the swollen end of a 

 hypha consisting of one or four cells and giving rise to branches called 

 sterigmata, each of which cuts off at its tip a spore, called a basidio- 

 spore. In addition to the basidiospores, some forms also produce 

 spores termed chlamydos pores. 



SUB-CLASS A. PROTOBASIDIOMYCETES 

 (Basidium four-celled, each bearing a spore) 



Order i. Ustilaginales, the smuts. Destructive parasites which 

 attack the flowers of various cereals, occasionally other parts of these 

 plants. Example: Ustilago Maydis, the corn smut. The basidio- 

 spores in this group are borne on promycelia. 



Ustilago Maydis (Ustilago Zeae) (Corn Smut). Corn smut is a 

 destructive parasite which for a long time was supposed to be con- 

 fined to the Indian Corn, but which now is known to occur on 

 Mexican Grass. It is the only smut useful in medicine. The 

 mycelium of the fungus extends through all parts of the infected 

 host through the intercellular-air-spaces and produces large tumor- 

 like masses on the ears, tassels, husk, leaves and stem. Each mass is 

 filled with spores and covered with a tightly appressed membrane 

 which has a whitish appearance like German silver. The spores 

 are at first a dark olive-green, but on maturity are dark brown. 

 They are sub-spherical and show prominent spines. They arise 

 by the division of the septate mycelium into thick-walled echinulate 

 resting spores called chlamydos pores or brand spores. These spores 

 fall to the ground and pass the winter. In the spring each germi- 

 nates into a three- or four-celled filament called a promycelium, from 

 the cells of which basidiospores arise. The basidiospores develop a 

 mycelium which penetrates the seedling of the host plant. 



