234 



CLASS ICOSANDRIA. 



We have now finished a review of the first ten classes, or 

 the first group of classes, those which depend upon the siii;l' 

 circumstance of the number of separate stamens ; in our next 

 lecture we shall consider the two classes which depend on tlie 

 number and insertion of the stamens. 



LECTURE XXX. 



CLASS XI. ICOSANDRIA. 



Fig. 115. 



In the class now before us, the num. 

 ber of stamens is not the characteristic 

 mark of distinction ; this consists in the 

 manner of the insertion of these or- 

 gans. In the analysis of the rose, 

 you have already become acquainted 

 >vith the leading features of this class, 

 and will, therefore, the less need a 

 minute detail of these elementary dis- 

 tinctions. 



Had we followed the classification, 

 which has, until recently, been admitted 

 by writers on botany,we should liavehad 

 another class to examine before we came to Icosandria ; this was 

 called Dodecandria, from Dodeka, 12, and andria, stamen ; it 

 was not, as you might infer from the name, confined to 12 sta- 

 mens, but contained from 10 to 20, without anyxegard to their 

 insertion, as standing either upon the calyx or receptacle. 

 This class produced confusion in the science of botany, for it 

 is found that plants having more than ten stamens, frequently 

 vary as to their number ; and there being no difficulty in dis- 

 tributing all plants of this class into the two next, it has been 

 by consent of most botanists left out of the classification ; and 

 the plants which it contained, arranged under Icosandria, if the 

 stamens were on the calyx, and Polyandria, if the stamens were 

 inserted upon the receptacle. The manner of insertion is al- 

 ways the same, and therefore there can be no confusion with 

 respect to determining the classes upon this principle. 



You will observe that this omission of one class changes the 

 numbers of the remaining classes ; as Icosandria, which was 

 formerly the twelfth, is now the eleventh, and so on with the 

 other classes. It is on account of these changes that we wish 



Class Icosandria Omitted class Names of classes expressive of their 

 character. 



