THE CLASSIFICATION OF PLANTS 



2157 



up their relationships. If his conclusions are adopted it will become 

 possible to form a tentative system which will include both recent and 

 extinct forms. 



THE ANGIOSPERMAE 



The classification of Angiospermae presents to the taxonomist by far the 

 greatest problem in systematic Botany. The group is so vast and the varia- 

 tions so great that atj first sight it appears virtually impossible to arrange 

 this heterogeneous collection in any satisfactory order. In early times, as we 

 have already pointed out in Chapter III, the study of plants was so closely 

 bound up with their use in medicine that descriptions of plants were 

 necessary and their arrangement in some system was inevitable. All the 

 systems proposed by earlier writers were more or less artificial, that is to 

 say they were based upon the con- 

 sideration of one character or a small 

 group of characters. Even Linnaeus 

 (Fig. 2064), although he did recognize 

 the imperfection of his sexual system, 

 attempted with its aid to classify 

 flowering plants upon the number 

 and arrangement of the stamens and 

 carpels, without paying any attention 

 to the general characteristics of the 

 plant as a whole. This system con- 

 tained twenty-four classes and while it 

 did succeed in delimiting certain fami- 

 lies quite satisfactorily, it cut right 

 across other families and divorced ob- 

 viously related plants from one another. 

 Thus the Linnaean Class 15, Tetrady- 

 namia, is exactly comparable with our 

 present Cruciferae, and similarly the 

 Compositae fall into his Class 19, 

 Syngenesia. On the other hand his Class 20, Gynandria, contains repre- 

 sentatives of both Monocotyledons and Dicotyledons. However, he recog- 

 nized fully the artificiality of this system and he attempted later to formulate 

 a natural system, in which plants were arranged under sixty-three family 

 headings, in accordance with their general affinities. He did not live to 

 complete this work but his " Fragmenta " provided the foundation for 

 later workers. 



The separation of Flowering Plants into Dicotyledons and Mono- 

 cotyledons, however, goes back before Linnaeus to the work of John 

 Ray (Vol. I, p. 42) who, in his " Historia Plantarum", 1686-1704, 

 divided plants into Herbs and Trees, and subdivided each group as 

 follows : 



Fig. 2064. — Cirolus Linnaeus (Carl von 

 Linne). (4fter a portrait in the 

 possession of the Linueau Society.) 



