38 Elementary Work in Botany. 



The numerous dot-like scars on the peduncle mark where 

 little clusters of flowers grew last June. How many clusters 

 were there ? How long was the compound bunch of flowers ? 

 How many and which flowers produced fruit ? Of what 

 use are the flowers which do not produce fruit ? Resolve 

 to find out by observing and thinking. Have faith in the 

 usefulness of every part of a plant to the plant itself. Parts 

 of plants or animals which cease to be useful gradually 

 become smaller, and finally, after many generations, dis- 

 appear. Thus many plants have useless rudimentary 

 organs. These can usually be easily recognized. The 

 kind of organ becoming abortive would be shown by its 

 position; its uselessness by its appearance. For example: 

 In all the collinsias there are four stamens, each growing 

 on the corolla between two of its five lobes. In the place 

 of a fifth stamen we find a short stem which, bearing no 

 anther, is useless as a stamen and probably has no other 

 use. But in pentstemon the fifth stamen becomes a bar to 

 prevent the entrance of unwelcome insects. In mimulus 

 the place of the fifth stamen is vacant. It has entirely dis- 

 appeared. Pentstemon furnishes an example of an organ 

 which has taken up a new kind of work. 



Dissect one of the terminal buds. Are the scales 

 like the leaves in pairs? How many? Do you find as 

 many pairs of tiny leaves in the bud as there were 

 pairs on the peduncle of last year? Draw the club-like 

 mass of flower buds in the center. Think of the growth 



