228 GENERAL MORPHOLOGY OF PLANTS 



It is not a very important matter as to which of these chapters 

 or groups we "read " first. But since the green algae represent 

 the most complete series from the simplest to the highest forms, 

 and because the liverworts, mosses, ferns and seed plants proba- 

 bly had their origin in lower green plants, the author prefers to 

 begin with the green algae. There is another advantage, also: 

 the simpler forms of the green algae which we study show very 

 much better than the others do the structure of the cell. 



PLANT KINGDOM. 

 SUBKINGDOM I. Thallophyta. 



THE ALGAE. 



Class I. Chlorophyceae. 



Subclass Protococcoideae. 



Subclass Conjugatae. 



Subclass Confervoideae 



Subclass Siphoneae. 

 Class II. Charophyceae 

 Class III. Cyanophyceae. 

 Case IV. Diatomeae; or Bacillariales. 

 Class V. Phaeophyceae. 

 Class VI. Rhodophyceae, 



