THE AMERICAN BOTANIST. 113 



most used is A triplex Brezueri an evergreen shrub of compact 

 growth but several other species may be used instead. All have 

 the ability to withstand heat, cold and drouth and are very ^de- 

 sirable for prairie regions. 



Sprengel and Pollination. — Sometimes the mere'^t 

 trifle has served to turn the attention of great minds into new 

 and important channels. It is said that Asa Gray became a 

 botanist from having his attention attracted for a moment by 

 the spring beauty (Claytonia) . In a similar way Christi n 

 Conrad Sprengel was started upon his brilliant investigations 

 into the relationships of flowers and insects by the contempla- 

 tion of the hairs on the petals of Geranium sylvaticum. lie 

 argued that the great Creator would have made nothing in 

 vain and therefore that even these tiny hairs must be useful. 

 Sprengel was a good Darwinian, if we may use that term of 

 one who died long before the "Origin of Species" was issued, 

 and though we now know that many plant structures are of no 

 use to the plants that possess them, we may rejoice that 

 Sprengel held the views he did since it resulted in our first real 

 knowledge of the pollination of flowers by insects. 



Perfume and the Color of Flowers. — It is stated on 

 the authority of a German botanist who has been investigat- 

 ing the subject that out of forty-three hundred species of 

 plants cultivated in Europe only four hundred and twenty 

 have an agreable perfume. As has long been understood, 

 flowers with white or cream-colored petals were found to be 

 most frequently fragrant after which come those with yellow, 

 red, blue and violet petals in the order named. Only thirteen 

 violet colored flowers had perfume, but this is partly due to 

 the fact that such flowers are not abundant in any flora. Of the 

 total number of flowers examined, twenty-three hundred had 

 no perceptible odor of any kind. This does not mean that 

 they have no odor, but simply that they have no odors that 

 man can detect; many of them may be fragrant to insects 



