OF THE CLASSIFICATION OF PLANTS, 165 



863. Species (§ 76). When He called plants into existence, in 

 their specific forms, He endowed each with the power of perpetuating 

 its own hind and no other, so that they have descended to us distin- 

 guished by the same characters and properties as at the beginning. 

 When, therefore, the student has formed acquaintance with any indivi- 

 dual plant, he is also acquainted with all other individuals belonging to 

 the same species. 



864. Fob example : a single plant oi white clover is a true representative of all 

 the millions of its kind that grow on our hiUa and in our meadows ; and a single 

 description of the white pine will answer in all essential points for every individual 

 tree of that noble species, in all lands where it is found. 



865. Gbneba. Although the species are separated from each other 

 by clear and definite distinctions, still they are found to exhibit also 

 constant affinities, whereby they stand associated into larger groups 

 called genera (§ 80). A genus, therefore, is an assemblage of related 

 species, having more marked afiinities with each other in general struc- 

 ture and appearance than they have with other species. 



866. Fob example : the white clover and ihe red (Trifolium repens and T. pra- 

 tense) are universally recognized as diiferent species, but of the same genus ; and a 

 single generic description of one plant of the genus Trifolium will convey intelli- 

 gence to a certain extent concerning every other plant belonging to its 150 species. 



867. Thus are the individual plants of the globe grouped by descent and resem- 

 blance, and comprehended under species ; and the species associated into higher 

 groups called genera. "An individual," says Prof. Forbes, " is a positive reality; 

 a species is a relative reality ; a genus is an idea — ^but an idea impressed on nature, 

 and not arbitrarily dependent on man's conceptions. An individual is one : a spe- 

 cies consists of many resulting from one ; a genus consists of more or fewer of these 

 manies resulting from one linked together, not by a relationship of descent, but by 

 an affinity dependent on a Divine idea." 



868. Okdees. But natural affinities do not end here. The genera are yet too 

 numerous for the ready and systematic study of the naturalist. He, therefore, would 

 generalize still further, and reduce the genera to still fewer and broader groups. 

 On comparing the genera with each other, he finds that they also possess in com- 

 mon certain important characters which are of a more general nature than those 

 which distinguish them from each other. By these general characters the genera 

 are associated into orders. 



869. For example: comparing such genera as the mustard, radish, cabbage, 

 cress, waU-flower, etc., it is seen that, whUe they differ sufficiently in their generic 

 characters, yet they all have certain marked resemblances, in their didynamous 

 stamens, siliquous fruit, whereby they are obviously associated into the sam« order 

 — ^the Cruciferffi. So, also, the pines, the spruces, the cedars, the larches, and the 

 cypress, while as genera they are obviously distinct, yet all bear cones of some 

 form, with naked seeds ;■ hence they are naturally grouped into one Order — the 

 Coniferffl. 



870. Classes. In like manner the Orders, by characteristics of resemblance still 

 more general, are associated into a few groups, each of great extent, called Classeei 

 whether natural or artifidaL 



