CHAPTER XV 



THALLOPHYTES (Concluded) 



Fungi (Thallophytes Lacking Food-making Pigments) 



General Discussion. The Fungi are a very large group of 

 Thallophytes. There are thousands of different kinds of Fungi. 

 Most people know some of the common forms, such as Toadstools, 

 Mushrooms, and Puffballs, and those who live on the farm are 

 probably acquainted with the Rusts and Smuts of our common 

 cereals. Most of the plant diseases are caused by Fungi. Like 

 the Slime Molds and Bacteria, they have no food-making 

 pigment and consequently are either saprophytes or parasites. 

 They attack both animals and plants. Plant Pathology, which 

 is a study of plant diseases, devotes some time to the study of 

 Slime Molds and Bacteria, but is concerned mainly with the 

 Fungi. They attack vegetables, grains, fiber plants, fruits, fruit 

 trees, and forest and shade trees. The destruction which they 

 cause is enormous. Some of the parasitic forms, however, are 

 harmless, and many of the saprophytic forms are beneficial. 



It is generally supposed that the Fungi are derived from the 

 Algae, having lost their chlorophyll and independent living. 

 Some of them have plant bodies, zoospores, sex organs, and sex 

 cells similar to those of the Green Algae, while some have sex 

 organs resembling those of the Red Algae, but have no resemblance 

 in other features. Some have become so modified by their de- 

 pendent habit of living that they have lost all of their alga-like 

 features. They have made no advancement in evolution, for 

 there is less differentiation of plant body in this group than 

 in the Algae, and methods of reproduction show no improvement, 

 but often are simpler than those of the Algae or have been lost 

 entirely. Those botanists who study plants mainly from the 

 standpoint of evolution devote very little time to the Fungi 

 because they have contributed nothing to evolution. But from 

 the economic standpoint, the Fungi are an exceedingly important 



351 



