152 



PLANT BIOLOGY 



As indicated above, many mushrooms are poisonous, but a fe\f 

 kinds are known to be edible. 1 Mushrooms are not especially nu- 

 tritious ; that is, they cannot take the place of the cereals and other 

 staple foods, but they serve to add to the variety of materials which 

 are more valuable for their flavoring qualities than for the quantity 

 of nutriment they contain. Commercially the cultivated mush- 

 room is of considerable importance, especially in Europe. Paris 

 is said to be the center for the sale of this product. In the year 



1901 it was estimated that 10,000,000 

 pounds of cultivated mushrooms 

 passed through the markets of Paris. 

 In this country the mushroom is of 

 commercial importance only in the 

 regions of the larger cities. 



164. Rusts and smuts. The 

 fungi known as rusts receive their 

 name from the rusty appearance in 

 an early stage of their growth which 

 they cause on the stems and leaves 

 of plants which they attack. The 

 cereals, wheat, oats, barley, and rye, 

 are the crops which this fungus in- 

 jures most. In the case of wheat, 

 half of the crop or even more may 

 be destroyed. 



The very suggestive name of smut 

 is given to another fungus which 



affects all the cereals named above, and corn as well. In the case 

 of corn, this plant often affects the ears as well. The name is 

 probably given on account of the appearance of the mass of black 

 spores. If one touches these spores, especially those of corn smut, 

 with the finger, and then rubs the finger on some white paper or 



1 So many deaths are caused by using poisonous instead of edible 

 mushrooms that it is never safe to eat wild forms until they have 

 been identified by an expert. 



FIG. 77. Corn smut on an ear 

 of corn. 



