426 THE HOME, FARM AND BUSINESS CYCLOPEDIA. 



form Orders or Families. While genera are groups of allied species, orders 

 are groups of allied genera, or, in reality, more comprehensive genera. 

 Thus, firs, pines, and larches belong to different genera, but all agree in 

 being cone-bearing, and are grouped under Conifene. The rose, the rasp- 

 berry, the bramble, the strawberry, the cinquefoil, the cherry, and the 

 plum, all agree in their general form and structure, and are united under 

 Rosacese. Certain genera have more points in common than others, and 

 are grouped together under sub-divisions of orders called Sub-orders. 

 Thus, the plum and the cherry have a drupe as their fruit, and are more 

 nearly allied to each other than they are to the apple ; again, the straw- 

 berry, raspberry, and bramble, are more allied to each other than to the 

 cherry or apple. We have thus Sub-orders of Rosacere namely, Amyg- 

 dalese, including the plum, peach, cherry, and almond ; Pomese, including 

 the apple, pear, medlar, and quince ; Potentillese, including the strawberry, 

 cinquefoil, and raspberry ; and Rosese, comprehending the roses. 



Certain orders, agreeing in evident and important general characters, 

 are united together so as to form Classes ; and sub-divisions of classes are 

 made in the same way as in the case of orders. There are thus Sub-classes 

 associating certain orders included in one class. 



The usual divisions are thus Classes, Orders, Genera, and Species. These 

 occur in all systems of classification. A more minute subdivision may be 

 made as follows : 



I. Classes. 



a. Sub-classes. 

 II. Orders or Families. 

 a. Sub-orders. 

 6. Tribes. 



c. Sub-tribes. 



III. Genera. 



a. Sub-genera. 



IV. Species. 



a. Varieties. 



An enumeration of the marks by which one Class, Order, Genus, or 

 Species, is distinguished from another is called its character. In giving 

 the characters of any division, we notice merely those which are necessary 

 to distinguish it from others. This is called the Essential Character. A 

 plant may also be described completely, beginning at the root, and pro- 

 ceeding to the stem, branches, leaves, flowers, fruit, seed, and embryo. 

 This is not essential, however, for the purpose of classification, and would 

 be quite superfluous in that point of view. In the character of classes the 

 important points of structure on which they are constituted are given. In 

 the character of orders (the ordinal character) we give the general struc- 

 ture of the included plants, especially of their flowers and fruit. In the 

 generic character we notice the modification of the ordinal character in a 



