212 
CLASS ICOSANDRIA. 
first group of classes, those which depend upon the single cir- 
cumstance of the number of separate stamens ; in our next lec- 
ture we shall consider the two classes which depend on the 
number and insertion of the stamens. 
LECTURE XXX. 
CLASS XI ICOSANDRIA. 
In the class now before us, the number of stamens is not the 
characteristic mark of distinction ; this consists in the manner 
of the insertion of these organs. In the analysis of the rose, 
which belongs here, you have already become acquainted with 
the leading features of this class, and will, therefore, the less 
need a minute detail of these elementary distinctions. 
Had we followed the classification, which has, until recently, 
been admitted by writers on botany, we should have had an- 
other 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 any regard 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 distribu- 
ting 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 w r ere 
inserted upon the receptacle. The manner of insertion is al- 
ways the same , and therefore, there can be no confusion with re- 
spect 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 
you to learn the classes by their appropriate names, as Monan- 
dria, Diandria, rather than to confine yourselves merely to the 
numbers, as 1st 2nd, &c. Besides, the name of each class is 
generally expressive of its character ; and will, when you un- 
derstand its derivation, convey to you the idea of this character, 
Class Icosandria — Not distinguished by number of stamens only — Omit- 
ted class — Names of classes expressive of their character. 
