76 BOTANY. 



To find which has the strongest affinity for the butter- 

 cup, the columbine or the poppy, all that is necessary, at 

 present, is, to ascertain which of them is nearest like the 

 buttercup in respect to cohesion and adhesion of the parts 

 of the flower. , 



On examination, you see that the columbine, like the 

 buttercup, is perfectly destitute of cohesion, while in the 

 poppy you have a coherent, or syncarpous, pistil. This 

 settles the question. The affinity of the columbine for 

 the buttercup is greater than the affinity of the poppy for 

 the buttercup. 



If you compare their leaves, you will find those of the 

 poppy more like buttercup-leaves than are those of the 

 columbine, but differences in leaf-structure do not usu- 

 ally signify as much in classification as differences in the 

 pistil. 



Compare, in the same way, the hollyhock and the 

 Saint-John's-wort with mallows, and decide which has the 

 strongest affinity for the mallows. 



Compare the flower of the locust and of the geranium 

 with that of the pea or bean. 



I mention these plants, not because they are useful 

 above all others for your purpose, but to start you in the 

 work. It really matters little what plants you take, if you 

 only carefully compare the group of characters of each 

 one with that of the others, and endeavor to discover the 

 affinities they present. 



EXERCISE XXIX. 

 How to begin Classification. 



If you have made the comparisons pointed out in Ex. 

 XXVIII, you are prepared for an explanation of the plan 

 by which you are to begin to classify plants. As we made 

 use of the buttercup and columbine to learn the meaning 

 of affinity in botany, a little further statement about them 



