GENEBAL BOTANY 



SECTION I 



MORPHOLOGY 



The object of vegetable morphology is the scientific study of the forms 

 of plants. It does not attempt to discover the causes of the variation 

 in the forms, but rather has accomplished its purpose when it succeeds 

 in showing how one form may be derived from another. The basis of 

 morphological study is, accordingly, phylogeny (p 2). As phylogenetic 

 development can only be inferred, and cannot be directly followed, the 

 methods of morphology must also be indirect. They are dependent for 

 their successful application upon ontogenetic comparison ; for, in the 

 ontogenetic development (p. 2) of a plant, its phylogeny is, to a certain 

 extent, repeated, so that, by a comparison of transitional forms, it is often 

 possible to discover a connection between plants which are apparently 

 most dissimilar. As, however, the ontogeny of a plant is neither an 

 exact nor invariable repetition of its phylogeny, and as connecting links 

 between extreme forms are often wanting, the results of morphological 

 study are frequently imperfect and incomplete. Such parts or mem- 

 bers of plants which it is reasonable to presume have had a common 

 origin are distinguished as Homologous ; those which, while probably 

 having different origins, yet exercise the same functions, are termed 

 Analogous. Through the adaptation of different parts to the same 

 function, a similarity in both external form and internal structure often 

 results ; and in this way the correct determination of morphological 

 relationships is rendered extremely difficult. Only homologous parts 

 have the same morphological value. This homology is determined by 

 the facts of phylogeny and origin, and not by any correspondence in 

 function. On account, however, of the intimate relation existing 

 between the form and function, and the modifying influence of 

 the one upon the other, it will be necessary in the morphological 



