6 MANUAL OF BOTANY 



the above genera belong to the order Oompositce, they are at the 

 same time placed in two different sub-orders. Thus, one sub- 

 order, called the LiguliflorcB, includes the Chicory, Dandelion, 

 Sow-thistle, and Lettuce ; and another sub-order, the Tubuli- 

 florce, that of the Thistle, Burdock, and Chamomile. In like 

 manner, while we find the Plum, Strawberry, Easpberry, Eose, 

 and Apple, all belonging to the same order Bosaceai, some of 

 them have more resemblance to each other than to others. 

 Thus, the Plum has a drupaceous fruit, and is therefore placed in 

 a distinct sub-order, which is called Drupacece ; the Strawberry, 

 Easpberry, and Eose are much more like each other than they 

 are like the Plum or Apple, and they are put in a sub-order 

 called Bosce ; while the Apple, from the character of its fruit, 

 is placed in a sub-order termed Poinece. 



It is also found convenient to subdivide sub-orders into 

 Tribes, Sub-tribes, &o., by coUeoting together into groups 

 certain very nearly allied genera, but it is not necessary for 

 us to illustrate such divisions further, as the principles upon 

 which they depend have been now sufficiently treated of. 



4. Classes. — By a class we understand a group of orders 

 possessing some very important structural characters in common. 

 Thus we have the classes Monocotyledones and Dicotyledones, 

 which possess certain distinctive characters in their respective 

 embrj'os, &o. 



The Classes are also divided into Sub-classes, Series, Cohorts 

 or Alliances^, and other divisions, in the same manner as the 

 orders, genera, and species are subdivided ; but as the names of 

 such divisions vary in different systems, and are aU more or leas 

 artificial, it is not necessary for us, in this place, to dwell 

 upon them further. The classes themselves, in different 

 systems, are also generally arranged in more comprehensive 

 groups, which have been variously named Sub-kingdoms, 

 Groups, Divisions, Regions, Sub -divisions, &c. But as these 

 are also of different extent and variously defined by botanists, 

 we must refer to the several systems for particulars respecting 

 them. 



The following table wiU include all the more important 

 groups we have alluded to ; those in more general use being 

 indicated by capitals. 



