SECT. II. TAXONOMY AND PHYTOGBAPHY. 151 



pericarp is composed of two carpels blended together 

 into a single two-celled capsule, containing many seeds 

 attached to a central placenta. The other order (Gym- 

 nospermia) was so named from a mistaken opinion 

 that the seeds were destitute of any pericarp, or naked 

 (jv^vot-). In this order the pistil is composed of four 

 carpels, each containing a single seed, and agglutinated 

 together into a compound ovarium with one style. 

 As the fruit ripens, the carpels separate, and ulti- 

 mately become four nuts, seated at the bottom of 

 the calyx. The two orders are, therefore, readily dis- 

 tinguished, by the former containing only one seed- 

 vessel with many seeds, and the latter four seed-vessels 

 which resemble four naked seeds. 



The fourteenth class also contains only two orders, 

 which are characterised by the comparative lengths of 

 the seed-vessels. They are composed of two carpels 

 united by their edges, and are divided into two cells by a 

 transverse membranous partition (see art. 109- fig. 123.). 

 When the length of the seed-vessel exceeds its breadth 

 three or four times, it is termed a siliqua, and the 

 order to which it belongs is named " Siliquosa." When 

 the length and breadth of the seed-vessel are nearly the 

 same, the order is named " Siliculosa." These dis- 

 tinctions are apparent in the flower, from the earliest 

 stages of the ovarium, and long before it becomes a true 

 seed-vessel. 



In the sixteenth, seventeenth, and eighteenth classes, 

 the orders depend upon the number of the stamens ; 

 and in this respect they resemble the thirteen first 

 classes themselves. 



The nineteenth class was originally divided into six 

 orders ; in five of which the flowers were aggregated 

 into heads, and thence distinguished under the name 

 of "Polygatniaj" whilst the sixth contained those simple 

 flowers, whose anthers, as in the violets (Violse), were 

 more or less united. But this last order has been abolished 

 by the universal consent of botanists ; and the species 

 which it contained, are now referred to their position in 

 fc 4 



