124 CLASS D1DYNAMIA, 



CHAPTER XXI. 



THE CLASS DIDYNAMIA. 



This class and its 2 orders each embrace a very 

 natural and similar assemblage of plants. Tbe gen- 

 eral character of the flower, as we have elsewhere 

 already remarked, is its irregularity, being almost 

 universally ringent, gaping, or personate with the lips 

 closed. The corolla in all is monopetalous ; and the 

 stamina 4, in 2 pairs of unequal length, so situated in 

 consequence of the inequality of the corolla. This 

 distinction in the length or proportion of the stamens, 

 consequent on the peculiar trait of the corolla, is the 

 foundation of this class, and hence called Didynamia, 

 or 2 powers ; but, as in 2 very distinct natural orders 

 of the same class so characterized, there exists but 

 one pistillum, it became necessary to have recourse 

 to some other character for the foundation of the 

 orders, such a distinction is then very obvious in the 

 fruit ; for in the first order, including all the 4 sta- 

 mened Labiatje of the natural method of arrange- 

 «pent, in which, as in the following order, there is but 

 one style, there is always in the bottom of the calyx 

 4 apparently naked seeds, and hence the ordinal 

 name of Gymnospermia. But in the 2d order of 

 irregular flowers with didynamous stamens, the single 

 style is succeeded by a regular, and commonly 2- 

 celled capsule, containing abundance of small seeds 

 attached to a central receptacle. 



The 2 orders of this class, in a natural point of 

 view, are quite distinct from each other ; and, not- 

 withstanding the nominal similarity of the fruit in the 

 Asperifoli;e of Pentandria, which have also 4 car- 

 pels in the bottom of the calyx, no 2 families of 



