64 THE SECOND BOOK OF BOTANY. 



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 that of 

 the poppy. 



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-struct- 

 ure do not usually 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 gera- 

 nium with that of the pea or bean. 



I mention these plants, not because they are use- 

 ful 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 XVII. 

 Sow to begin Classification. 



If you have made the comparisons pointed out in 

 Ex. XVL, you are prepared for an explanation of the 

 plan by which you are to begin to classify plants. As 



