GENERAL PRINCIPIES 



has its axis horizontal. The upper petal (standard) is very 

 broad and stands erect, making the flower very conspicuous. 

 The two lateral petals (wings) form a horizontal platform upon 



FIG. 251. A row of the nets woven by the Caddice fly larvae, to catch food. 

 In the next figure three of the nets are seen from above. 



which an insect (bee) may conveniently rest when visiting the 

 flower for nectar. The two lower petals are slightly curled longi- 

 tudinally and have their concave faces toward each other (keel) , 

 so that they completely enclose the stamens and pistil. The 

 filaments of the ten stamens are all united, except the upper 



FIG. 252. Nets of Caddice worm. See Fig. 251. 



one, for most of their lengths. The ends only are free and 

 bend upward. The style also bends upward at the end. 

 When an insect like a bee visits the flower its weight presses the 



