CLASS ICOSANDRIA. 
LECTURE XXX. 
CLASS XL—ICOSANDRIA. 
Had we followed the classification which 
has, until recently, been admitted by writers 
on botany, we should have met with the class 
Dodecandria, from Dodeka , 12, and andria, 
stamen; it was not, as you might infer from 
the name, confined to 12 stamens, but contain¬ 
ed from 10 to 20, without any regard to their 
insertion. This class produced much confu¬ 
sion in the science; for it is found that plants 
having more than ten stamens, frequently vary 
as to their number there being no difficulty 
in distributing all plants of this class in the 
two next, it has, by consent of most botanists, 
been left out of the system; and the plants 
which it contained, are arranged under Ico- 
sandria, if the stamens are on the calyx , and Polyandria, if the sta¬ 
mens are inserted upon the receptacle. The 'manner of insertion is 
always the same in the same genus, 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 former¬ 
ly 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 Monandria, Diarndria, rather 
than to confine yourselves merely to the numbers, as 1st, 2d, &c. 
Besides, the name of each class is generally expressive of its cha¬ 
racter, and will, when you understand its derivation, convey to you 
the idea of this character, which, by the number alone, could not be 
done ; for example, the term tenth'class, conveys no idea but that of 
mere number; but the classical name Decandria, from deka , ten, 
and andria , stamens, reminds you of the circumstance on which the 
class is founded. 
The name Icosandria, from eikosi , 20 , and andria , stamens, seems 
not, however, exactly well chosen to represent the eleventh class, 
which is not confined to twenty stamens, having sometimes as few 
as ten, and in some cases nearly a hundred stamens. An American 
botanist* has proposed to call the class Calycandria , from calyx and 
andria, as the insertion of the stamens on the calyx is the essential 
circumstance on which the class depends; this change has been ap¬ 
proved, but the old name is still used. Thus, with respect to the 
name given to the great American continent, all allow it should have 
been Columbia, after Columbus, its discoverer ; but when once cus¬ 
tom has sanctioned a name, it becomes very difficult to overcome 
this authority. 
Order Monogynia. 
We meet here with the Prickly-pear tribe, ( Cactece ,) in which the 
Cactus is the most important genus. Jussieu included in this natural 
order, the currant and gooseberry ; but Lindley has formed them 
* Darlington. 
What is said of the class which is omitted in this part of the system ?— Why is it 
important to learn the appropriate names of the classes, rather than their numoers 1 
—What name has been proposed as a substitute for Icosandria ?—The Cactus tribe. 
