CONSPICUOUS FLOWERS RARELY VISITED BY INSECTS 153 



which most strongly sustained his views, while a few particulars 

 were given in regard to his other experiences. •» 



There will be described in the present paper a few of the more 

 interesting experiments performed by Plateau on relatively 

 large and brilliantly colored flowers seldom visited by insects, 

 following which will be given the observations of the writer on 

 similar flowers. Among the familiar species selected by Plateau 

 was a purple-flowered variety of Clematis Jackmanni Jack., a 

 hardy perennial vine widely cultivated both in Europe and Amer- 

 ica. The flowers are nectarless, but bees obtain from them a 

 small amount of pollen. A vine of C. Jackmanni superba is 

 described by Plateau as covering a wall three meters in height 

 and displaying many hundred magnificent blue-violet flowers, 

 which are said to have been wholly ignored by insects. On a 

 very warm clear day anisette was introduced into eleven flowers, 

 near each other, and constituting a group by themselves. In 

 the hour following, they were visited by fourteen bumblebees 

 and six flies belonging to the family Syrphidae. In four instances 

 bumblebees examined adjacent flowers which remained in their 

 natural condition. 



The facts related by Plateau are not called in question; but 

 it should be noted again that the ungarnished flowers possessed 

 only conspicuousness and pollen, while the' eleven flowers contain- 

 ing anisette possessed conspicuousness, pollen, an agreeable 

 odor and a sweet liquid; evidently color was not here brought 

 directly into competition with odor. Let us now endeavor to 

 determine whether the purple flowers are as completely neglected 

 by insects as Plateau supposed; and whether insects can not be 

 induced to visit them in large numbers without the addition 

 of an agreeable odor! The purple-flowered Clematis on which 

 my observations were made was a small vine bearing only eleven 

 flowers wholly or partially expanded. The flowers were of large 

 size, pale purple, nectarless, and odorless. As regards brilliancy 

 of coloring and number, they were at a great disadvantage 

 compared with the inflorescence described by Plateau. They 

 were very frequently examined during the entire period of 

 blooming. 



» Plateau, F., " Recherches experimen tales sur les fleurs entomophiles peu 

 visitees par les insectes rendues attractives au moyen de liquides sucres odorants," 

 Mem. de I' Acad. roy. de Belgique, 2me sen, 2:1-55, 1910. 



