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BOTANY FOR BEGINNERS-VII 



By WiLLARD N. Clutk. 



HEN the beginner takes up a scientific key, it is enough 

 for him if he is able to trace his plants correctly. He 

 rarely bothers about how the key is constructed or what char- 

 acters the maker seized upon to break up the world of plants 

 into smaller and more manageable groups. As a matter of 

 fact, it is of little consequence what distinctions are used, pro- 

 vided always that they unerringly refer each species to its 

 proper group. In a key to the common lobelias, for instance, 

 it would be quite sufficient to' use "flower scarlet" to distin- 

 guish the cardinal flower from its relatives, but the same dis- 

 tinction could not be made among the violets because there 

 are no red species. Nor would such a division answer for 

 large groups since it would place entirely unrelated forms to- 

 gether. 



In selecting distinguishing features for their groups, the 

 key-makers pretty generally adopt such marks as will place re- 

 lated plants together, but the trouble is to hit upon characters 

 that will indicate relationship. To group together all plants 

 possessing palmate leaves would be a mistake, for single 

 plants in any natural group may possess such leaves. Charac- 

 ters taken from the flowers, however, are more certain. It is 

 a commonplace to say that entire families have the same type 

 of flower. We see this in the mints, lilies, roses, peas and 

 mustard families, to mention only a few; we therefore find 

 the main divisions of the keys depending on some character 

 of the flower. 



