SPECIES AND GENERA. Ill 



CHAPTER XV. 



SYSTEMATIC BOTANY. 



§1. OF THE CLASSIFICATION OF PLANTS. 



330. Systematic Botany relates to the arrangement of plants 

 into groups and families, according to their characters, for the 

 purpose of facilitating the study of tlieir names, affinities, habits, 

 history, properties, and uses. 



331. The student in botanical seience is introduced into a boundless field of 

 inquiry. The subjects of his research meet liim at every step : they clothe the 

 hill and the plain, the mountain and the valley. They spring up in the hedges 

 and by the wayside ; they border the streams and lakes, and sprinkle over its sur- 

 foce; they stand assembled in vast forests, and cover with verdure even the 

 depths of the ocean ; they are innumerable in multitude, infinite in variety. Yet 

 the botanist proposes to acquaint himself with each individual of tliis vast king- 

 dom, so that he shall be able readily to recognize its name, and all that is either 

 interesting, instructive, or useful concerning it, whenever and wherever it is pre- 

 sented to his view. 



332. Now it is obvious, that if the student should attempt the accomplishment 

 of this task by studying each individual plant in detail, whether with or without 

 the aid of books, the longest life would scarcely be sufficient to make a begin- 

 ning. 



333. But such an attempt would be as unnecessary as fruitless. The Author 

 of Nature has grouped these mjTiads of individuals into species (50). Wlien 

 he called them into existence in their specific fonns, he endowed each with the 

 power of perpetuating its own kind and no other, so that they have descended to us 

 distinguished by the same differences of character and properties as at the begin- 

 ning. "UTien, therefore, the student has become acquainted with any one indi- 

 ^•idual plant, he is also equally acquainted with all others belonging to the same 

 species. 



a. Thus a single stalk of white clover becomes a representative of all the mil- 

 lions of its kind that grow on our hills and plains, and a single description of the 

 ivhite pine will answer, in all essential points, for every individual tree of that 

 ancient and noble species, in all lands where it is found. 



334. Again, the species themselves, although separated from each other by 

 obvious differences, still are found to exhibit many constant affinities, whereby 

 they are formed into larger groups, called genera (52). Thus the white clover 

 and the red (Trifolium repens and T. pratense) are universally recognized as of 

 different species, but of the same genus ; and a single generic description of any 



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