146 



INTRODUCTION TO BOTANY 



of the evening primroses, honeysuckles, and Jimson weeds 

 (fig. 131). The nectar from such flowers can best be reached 

 by insects with a very long proboscis, like that of the butter- 

 flies or the hawk moths (fig. 131). Many flowers with long 

 corolla tubes are also visited by humming birds. 



Red-clover flowers are pollinated 

 mainly by bumblebees. What 'effect 



n 



pr 



FIG. 130. A, head of cab- 

 bage butterfly ; .B, head 

 of honeybee 



a, antennae ; pr, proboscis, 

 or sucking organ. The pro- 

 boscis of the butterfly is 

 represented as coiled into 

 a spiral. Both somewhat 

 magnified. After Behrens 



FIG. 131. Pollination of flower of Jimson 

 weed (Datura) by a hawk moth 



The nectar is inaccessible to ordinary insects 



upon the crop of clover seed have field mice, which destroy 

 the nests of bumblebees ? How would red clover thrive if 

 introduced into a country where there were no bumblebees ? 

 139. The arum ; a pitfall flower cluster. Our common jack- 

 in-the-pulpit is the most familiar American member of the 

 great (mostly tropical) Arum family. The over-arching hood 

 and the tube from which it springs inclose a club-shaped 

 axis on which are borne many inconspicuous flowers. Great 



