PLANT BIOLOGY 



CHAPTER I 

 NO TWO PLANTS OR PARTS ARE ALIKE 



FIG. i. No Two BRANCHES ARE ALIKE. 

 (Hemlock.) 



IF one compares any two plants of 

 the same kind ever so closely, it will be 

 found that they differ from each other. The 

 difference is apparent in size, form, color, mode 

 of branching, number of leaves, number of flowers, vigor, 

 season of maturity, and the like ; or, in other words, all 

 plants and animals vary from an assumed or standard type. 

 If one compares any two branches or tivigs on a tree, it 

 will be found that they differ in size, age, form, vigor, and 

 in other ways (Fig. i). 



If one compares any two leaves, it will be found that 

 they are unlike in size, shape, color, veining, hairiness, 

 markings, cut of the margins, or other small features. In 

 some cases (as in Fig. 2) the differences are so great as to 

 be readily seen in a small black-and-white drawing. 



