166 



CLASS ICOSANDRIA- 



LECTURE XXX. 



CLASS XI. ICOSANDRIA. 



Fig. 135, 



Had we followed the classification which 

 has, until recently, been admitted by writeris 

 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 

 y insertion. This class produced much confu- 

 ^^ sion in the science ; for it is fovmd that plants 

 having more than ten stamens, frequently vary 

 as to their numbei' ; — 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, Diandria, 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 thf. 

 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, (Cactea:,) in which the 

 Cactus is the most important genus. .Tussieu included in this natural 

 order, the currant and gooseoerry ; 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 numbers? 

 —What name has been proposed as a substitute for Icosandria 7— The Cactus tribe. 



