300 BOTANY 



Cryptogams there were at that time but comparatively few forms 

 known, and the complicated methods of reproduction of this now large 

 class were absolutely unknown. In contrast to the Cryptogams, the 

 other twenty-three classes were distinguished as Phanerogams or plants 

 whose flowers with their sexual organs could be easily seen. Linnaeus 

 divided the Phanerogams, according to the sexual character of their 

 flowers, into such as possessed hermaphrodite flowers (Classes I.-XX.), 

 and those in which the flowers were unisexual (XXI. -XXIII.). Plants 

 with hermaphrodite flowers he again divided into three groups : those 

 with free stamens (I.-XV.), which he further distinguished according 

 to the number, mode of insertion, and relative length of the stamens ; 

 those with stamens united with each other (XVI. -XIX.) ; and those in 

 which the stamens were united with the pistil (XX.). Each of the 

 twenty-four classes were similarly subdivided into orders. While 

 some of the classes and orders thus constituted represent naturally 

 related groups, although by the method of their arrangement in the 

 artificial system they are isolated and widely removed from their 

 proper position, they include, for the most part, plants which phylo- 

 genetically are very far apart. 



Linnaeus himself (1738) felt the necessity of establishing natural 

 families in which the plants should be arranged according to their " re- 

 lationships." So long, however, as the belief in the immutability of 

 species prevailed, the adoption of a system of classification expressive 

 of relationship and family could have no more than a hypothetical 

 meaning, and merely indicated a supposed agreement between plants 

 having similar external forms. A true basis for a natural system of 

 classification of organisms was first afforded by the theory of evolution. 



The system adopted as the basis of the following description and 

 systematic arrangement of plants is the natural system of Alex- 

 ander Braun, as modified and further perfected by EiCHLER and 

 others. 



According to this system we have to distinguish between CRYPTO- 

 GAMS as the lower division, and Phanerogams as the higher division 

 of the plant kingdom. 



SECTION I 



CEYPTOGAMS 



The Cryptogams include an extraordinary variety of the most different 

 plant forms, extending from unicellular organisms to plants exhibiting 

 segmentation into stem, leaf, and root. The Cryptogams, however, are 

 collectively distinguished from Phanerogams by the mode of their 

 dissemination by SPORES, in contrast to that of the Phanerogams, which 



