184 SYSTEMATIC BOTANY. 



454. Into this vast kingdom of Nature the student is introduced, and pro- 

 poses to acquaint himself with each and every object. How shall he begin? 

 Evidently he must begin with the individual a single individual plant. But 

 (thanks to Him who created both the plant and the mind the object and the 

 subject), he is not left to continue the study in a method so endless and so 

 hopeless. As if in special regard to the measure of the human intellect and 

 the means of its culture, the Great Author of Nature has grouped these 

 myriads of individuals into the following divisions : 



455. Species are individuals of a common origin or 

 parentage capable of producing their kind, though fre- 

 quently differing from each other in size, form, and 

 other unimportant characters. A species has been de- 

 nned as a "succession of individuals which reproduces 

 and perpetuates itself." 



456. Variety, or Race, is a sub-species. This term 

 is applied to individual plants that possess marked 

 variations from specific characters, but not of suffi- 

 cient constancy to entitle them to the rank of species. 

 These differences are frequently brought about by the 

 quality of the soil or locality, but especially by culti- 

 vation. 



Race characters are perpetuated and become con- 

 stant by grafting, budding, and carefully selecting 

 well-marked individuals from which to obtain seed. 



The desirable characters of most of our fruits and 

 table vegetables are made constant in this way. 



457. Genus is the name for a Group of individual 

 plants which resemble each other in the form and 

 structure of their organs of Fructification and Repro- 

 duction. 



Illustration The individuals of the Crowfoot Kind differ in the size and 

 color of their flowers, some of which are yellow, others white ; in the size and 

 form of their stems, some of which grow erect, others prostrate and in the 

 shape of their leaves. Their organs of Fructification, however, are all con- 

 structed upon the same plan, and the function of polination is performed in 



