288 SYSTEMATIC BOTANY 



subclass divided into three great groups : Sympetalous 

 (called also Monopetalous and Gamopetalous) ; Apopetal- 

 ous (or Polypetalous); and Apetalous. A glance will refer 

 our blossom to the sympetalous or monopetalous group, 

 which we find divided into two sections, characterized by 

 the superior or inferior ovary (Sees. 289, 294). A little 

 examination will show that the morning-glory belongs to 

 the former class, which is in turn divided into two sections, 

 according as the corolla is regular, or more or less irreg- 

 ular. We see at once that we must look for our specimen 

 in the former class. This we find again subdivided into 

 four sections according to the number and position of the 

 stamens, and we find that the morning-glory falls under 

 the last of these ; " Stamens as many as the lobes or parts 

 of the corolla and alternate with them." A very little 

 further search brings us to the family Convolvulacea, and 

 turning to that title in the descriptive analysis, page 306, 

 we find under the genus, Ipomea, a full description of the 

 common morning-glory, in the species Ipomea pnrpurea, 

 and of the sweet potato in the species Ipomea batatas. 



