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CHAPTER XV. 

 CLASSIFICA TION. 



Under the head of Classification we include the grouping of 

 plants into classes according to their affinities. There are two 

 great systems of classification, the Artificial, or (as it is often 

 called) the Linnaean, and the Natural. In the former case the 

 plants are arranged simply according to the number, position, 

 and relation of their stamens and carpels ; in the second case 

 the general structure and arrangement of the plant as a whole 

 is taken into account. The result is that although the Artificial 

 system is a most useful one for the purpose of tracing out a 

 flower whose name we may wish to discover, yet since it de- 

 pends solely on the arrangement of one set of organs, it often 

 separates plants which are evidently closely allied, and on the 

 other hand unites those which possess no common properties 

 beyond the structure of their flowers. For these reasons, for the 

 purposes of classification, the Natural system is now always 

 employed. 



The sub-kingdom of Flowering Plants is divided into two 

 classes, the Dicotyledons and Monocotyledons, most of the 

 distinctive characteristics of which we have already noted, and 

 hence it will only now be necessary to tabulate them as follows. 



DICOTYLEDONS. MONOCOTYLEDONS. 



Embryo with two cotyledons. Embryo with one cotyledon. 



Primary root-growth exorhizal. Primary root-growth endorhizal. 



Growth of wood with open Growth of wood with closed bundles, 



bundles, exogenous. • endogenous. 



Leaves net-veined. Leaves parallel-veined. 



Parts of the flower arranged (as- Parts of the flower arranged in 



a rule) in fours or fives. threes. 



Each of these classes is divided into sub-classes, of which 



