428 THE HOME, FARM AND BUSINESS CYCLOPAEDIA.. 



is to be referred, he does not thereby become acquainted with its struc- 

 ture and properties ; plants diametrically opposed in these respects may 

 be associated together. When lie determines, on the other hand, the place 

 of a plant in the natural system, he necessarily acquires a knowledge of 

 its structural relations and affinities. Hence a knowledge of the latter 

 system must be the aim of the botanical student. 



NATURAL SYSTEM OF CLASSIFICATION. 



In arranging plants according to the natural system, the object is to 

 bring together those which are allied in all essential points of structure. 

 It is called natural, because it professes to follow the system of Nature, 

 and thus takes into account the true affinities of plants on a comparison 

 of all their organs. One of the first natural methods of classification was 

 that proposed by Ray, about 1682. He separated flowering from flower- 

 less plants, and divided the former into Dicotyledons and Monocotyledons. 

 His orders were founded on correct views of the affinities of plants, and 

 he far outstripped his contemporaries in his enlightened views of arrange- 

 ment. He may be said to have laid the foundation of that system which 

 has been elucidated by the labours of Jussieu, De Candolle, Brown, Lind- 

 ley, Endlicher, and others. 



In arranging plants according to a natural method, we require to have 

 a thorough knowledge of structural and morphological botany, and hence 

 we find that the advances made in the latter departments have materially 

 aided the efforts of systematic botanists. We may regard plants in vari- 

 ous points of view, either with reference to their elementary tissues, their 

 nutritive or their reproductive organs. The first two are the most impor- 

 tant, as being essential for the life of individuals, while the latter are con- 

 cerned in the propagation of the species. These sets of organs bear a 

 certain relation to each other, and we find that plants may be associated 

 by a correspondence in all of them. In comparing the characters of plants, 

 we must take care that we contrast organs belonging to the same class of 

 functions, and the value of the characters must depend upon the impor- 

 tance of the functions performed by the organs. 



Cellular tissue is reckoned of the highest value, as beiug of universal 

 occurrence, and as carrying on, in many instances, all the functions of 

 plants. In considering the elementary tissues alone, we divide all plants 

 into Cellular and Vascular the former including the lower tribes of 

 flowerless plants, such as lichens, seaweeds, and mushrooms, the latter in- 

 cluding the higher flowerless plants with scalariform vessels, and all the 



