362 



FUNGI 



FIELD TRIP FOR THE STUDY OF LICHENS 



After a rainy period, examine trees, rocks, old fences, posts, and sim- 

 ilar places for lichens. Note the form, color, and kinds of trees having 

 the greatest number of lichens ; the trees having the smallest number, and 

 the side of the tree having the greatest number. Make the same exam- 

 ination during a dry period. 



SUMMARY 



Fungi are plants similar in structure to the algae, but 

 they lack chlorophyll. On this account fungi cannot 

 make their own food, but always have to use that pre- 

 pared by another organism. As 

 they lack chlorophyll, fungi 

 cannot use carbon dioxide, and 

 as a result that which they 

 produce by respiration is cast 

 off into the air, as is the case 

 with animals and with green 

 plants placed in the dark. 



The fungi which are most 

 important economically are the 

 yeasts used in making bread, 

 or beer and other fermented 

 liquors ; the edible mushrooms ; 

 those that spoil food, as bread mold, and those which 

 cause plant diseases, such as corn smut and wheat rust. 

 Fungi reproduce by means of spores. The mutually help- 

 ful relation in which fungi and algse live in the lichen is 

 called symbiosis. Animals which show the same relation 

 are of little economic importance in this country. 



Fiqure 388. — Spores of Corn 

 Smut. 



A farm fungus. 



QUESTIONS 



What is the color of fungi ? Are they ever green ? Why not ? How 

 does their food differ from that of green plants ? How does the yeast 

 plant produce changes in flour ? In malt ? How does the work of bread 



