THE LOWER EUNGl 



PHYCOMYCETES 



CHAPTER I 

 INTRODUCTION 



As botanists are not yet in complete agreement with respect 

 to the Hmits and interrelationships of the various groups of 

 primitive plant life, it is necessary that the extent of the lower 

 fungi as here understood be indicated. It is desirable also that 

 at least brief consideration be given to the groups of organisms 

 which lie near them in the classification. 



Thallophytes. — The plant kingdom is divided by systematists 

 into several large primary subdivisions. The lowest of these 

 embraces all the primitive forms of plant life, and is named by 

 most writers the Thallophyta. In this large and diverse assem- 

 blage the vegetative portion of the plant is usually very simple in 

 type, and in general lacks the definite differentiation into root, 

 stem, and leaf which characterizes higher plants. This simple 

 vegetative plant body has been termed the thallus; hence the 

 name Thallophyta meaning thallus plants. In the group as a 

 whole the thallus is extremely simple, and in many of the lower 

 forms consists of only a single cell. Among the higher forms 't 

 sometimes shows considerable differentiation. Moreover, in 

 some groups of plants above the Thallophyta the vegetative 

 body is simple and has been called the thallus. In such cases 

 the relative simplicity of the reproductive processes serves to 

 separate the Thallophyta from higher forms. 



Although no two of the various standard classifications of 

 lower plants agree in detail, the following brief outline of the 

 major subdivisions of the Thallophyta represents in the main the 

 most generally accepted arrangement, and will, in any case, 



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