Chapter VII. 



Smuts and Rusts. 



Higher fungi. The plants already described may suffice as 

 examples of the algal fungi. The higher or "true" fungi con- 

 stitute a very large group of various forms, some of which are 

 parasitic, attaching themselves to the bodies of plants or of 

 animals, while others live upon decaying organic matter. No 

 fungus has leaf-green and consequently no fungus can manu- 

 facture starch out of carbonic-acid-gas and water, but its nutri- 

 tion is rather animal-like, in that there must be provided more 

 -complex food-substances. A fungus cannot live on a diet prin- 

 cipally of air, salts and water as do the algae, mosses, ferns and 

 most flowering plants. 



Smuts. Among the higher fungi the smuts are a well-known 

 group. Every one is familiar with the smut of Indian corn 

 which occasions the appearance of great distorted kernels, many 

 times as large as the ordinary ones, composed almost entirely 

 of smut threads and a very copious black mass of smut spores. 

 Other kinds of smut are found upon oats, upon wheat, upon 

 millet-grass, upon sedges, and upon sand-burrs. Generally the 

 smut spore-masses develop themselves in the seed-areas of 

 plants, and substitute for the seed their own fruit-bodies. 

 Hence the smut fruit-body in the Indian corn takes the form 

 of a greatly enlarged corn kernel and the stinking smut of wheat 

 fills the wheat grain with a mass of spores, allowing the wheat 

 to produce only the shell of the fruit while the interior is a solid 

 mass of smut. Sometimes a whole flower-cluster is infected as 

 in the sand-burr smut. In a few plants the stamens are attacked 

 by smut fungi and an example is furnished by the corn-cockle, 

 a weed belonging to the pink family and to be met with in cul- 

 tivated fields. Here the stamens, when mature, open in the or- 

 dinary way to cast out their pollen, but if the smut that some- 



