:^30 BOTANY i-aht ii 



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

 with hermaphrodite flowers lie again divided into three groups : those with free 

 stamens (II.-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 was 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 phylogenetically are very far apart. 



LiNN^us himself (1738) felt the necessity of establishing natural 

 families in which the jjlants should be arranged according to their 

 " relationships." So long, however, as the belief in the immutability 

 of species prevailed, the adoption of a system of classification ex- 

 pressive of relationship and family could have no more than a hypo- 

 thetical 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 aflbrded 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 Alexander 

 Braun, as modified and further perfected by Eichler, Engler, 

 Wettstein, 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 

 CRYPTOGAMS 



The Ciyptogams include an extraordinary variety of the most 

 different plant forms, ranging 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 is effected by seeds ; sjjores are formed also by 

 Phanerogams, but they are not the immediate cause of the origin 

 and development of new individuals. Seeds are multicelluhir bodies, 

 within which is included the multicellular rudiment or embryo of a 

 plant ; while spores, which, in the case of the Cryptogams, become 

 separated from the mother plant, and give rise to a new and 

 independent organism, are unicellular structures. Cryptogams could 



