~ ORDERS. 117 
eo 
characters of these, botanists have bestowed the highest degree 
of attention, and the student’s progress will depend chiefly upon 
his acquaintance with them. 
356. Orders are formed by associating together those genera 
which are the most nearly allied to each other, or to some one 
genus previously assumed as the type. Therefore, as the spe- 
cies form genera, so genera form orders. 
357. In systematic works, the orders are also associated on 
natural principles into alliances, groups, &c., which are inter- 
mediate between these and the sub-classes, and are designated 
numerically, thus, group Ist, group 2d, &c., or by names derived 
from a leading order. 
- 358. In regard to their extent,the orders differ very widely, 
some consisting of a single genus, as Sarraceniacee, while 
others comprehend hundreds of genera, as Composite. For 
convenience’ sake the larger orders are broken up into sub- 
orders, or tribes. 
359. The Natural System, with its classes,and subordinate 
divisions, may be exhibited in one view; 
The VecEeTAaBLE Kinepom is separated 
1st, into Grand Divisions and Subdivisions. 
2nd, “ Classes. 
3d, “  Sub-classes, Alliances, and Groups. 
4th, “ Orders and Sub-orders. 
5th, “ Genera and Sub-genera. 
6th, “ Species and Varieties, and 
7th, “ Individuals. 
