LESSON 28.] ORDERS, CLASSES, ETC. 177 



other : this group, therefore, answers to what is called a Tribe ; and 

 the Rose itself stands for another tribe. But we further observe 

 that the Apple genus, the Hawthorns, the Quince, and the June- 

 berry, though of the same order, and nearly related among them- 

 selves, differ yet more widely from the Rose and its nearest relations; 

 and so, on the other hand, do the Plum and Cherry, the Peach and 

 the Almond. So this great Rose Family, or Order, is composed of 

 three groups, of a more marked character than tribes, groups 

 which might naturally be taken for orders ; and we call them Sub- 

 orders. But students will understand these matters best after a few 

 lessons in studying plants in a work describing the kinds. 



508. Classes, These are great assemblages of orders, as already 

 explained (51 5). The orders of Flowering Plants are numerous, 

 no less than 134 being represented in the Botany of the Northern 

 United States ; but they all group themselves under two great 

 classes. One class comprises all that have seeds with a mono- 

 cotyledonous embryo (32), endogenous stems (423), and generally 

 parallel-veined leaves (139) ; the other, those with dicotyledonous 

 embryo, exogenous stems, and netted-veined leaves ; and the whole 

 aspect of the two is so different that they are known at a glance. 



509. Finally, these two classes together compose the upper Series 

 or grade of Flowering or Phcenogamous Plants, which have their 

 counterpart in the lower Series of Flowerless or Cryptogamous Plants, 

 composed of three classes, and about a dozen orders. 



510. The universal members of classification are CLASS, ORDER, 

 GENUS, SPECIES, always standing in this order. When there are 

 more, they take their places as in the following schedule, which 

 comprises all that are generally used in a natural classification, 

 proceeding from the highest to the lowest, viz. : 



Series, 



CLASS, ~^>t 

 Subclass, 



ORDER, or FAMILY, ^v^ v*^-^ 



Suborder, 

 Tribe, 



Subtribe, 

 GENUS, 



Subgenus or Section, 

 SPECIES, 



Variety, ^j : 

 S&F-9 



