PRELIMINARY DISCOURSES. XXXI 



on tlie absence of visible flowers. The first 13 classes are disposed 

 numerically, according to the number of distinct stamens, of about 

 equal length, inserted on the receptacle of each flower, with the 

 exception of the 12th (Icosandria], in which the stamens (occasion- 

 ally few, and sometimes very numerous though usually about 

 twenty, as the name indicates,) are inserted on the calyx; and it is 

 this insertion which constitutes the essential character of the 12th 

 Class. From Class 1 to 10, inclusive, the number of stamens is the 

 same as the number of the Class. The llth Linnaean Class (called 

 Dodecandria meaning 12 stamens) was made to comprise all plants 

 with more than 10 and less than 20 stamens; but such plants 

 being few in number have been referred (very judiciously, as I 

 think), by some modern Botanists, to the Class Polyandria, which, 

 consequently, contains all plants with more than 10, distinct, or 

 separable stamens, inserted on the receptacle. The Class next after 

 Polyandria (called Didynamia 14th of LINNAEUS), contains plants 

 having 4 distinct stamens in unequal pairs one pair being regularly 

 longer than the other; and the succeeding Class (Tetr adynamia,) 

 has 6 distinct, unequal stamens, 4 of them being longer, and 2 

 opposite ones short. The next three Classes are founded on the 

 union of the stamens, or rather of their filaments the anthers being 

 free: the Class Monadelphia usually having numerous stamens, 

 with the filaments all united together in a tube, or single set ; the 

 Class Diadelphia having mostly 10 stamens, with the filaments 

 united in two sets (usually 9 and 1), and the corolla generally in the 

 form called papilionaceous, or butterfly-shaped ; and the Class Polya- 

 delphia having numerous stamens, united in three or more sets, 

 but, as the union is often slight, and the filaments especially in 

 dried specimens incline to separate, the plants of this Class have 

 been referred to Polyandria. The Class next following those 

 with united filaments, is a very large one, with united anthers 

 (named Syngenesia], and what are called compound flowers i. e. the 

 floral developments (which are often large and showy,) are really 

 composed of many little flowers, densely crowded in heads, on a 

 common receptacle, the heads being embraced, or supported, by 

 numerous bract-like leaflets, which constitute what is termed the 

 involucre. The succeeding Class (Gynandria,] has the stamens 

 inserted on the pistils or those organs so united, and often so 

 intimately blended, as to render them rather obscure, to the inex- 

 perienced observer. 



In the preceding Classes, the stamens and pistils are mostly in the 

 tame flower; but in the three following which conclude the 



