THE SYCAMORE "KEY" 



another of these bees engaged in seeking the 

 nectar and pollen of the flowers. (I may say- 

 here parenthetically that when these insects are 

 busy amongst the flowers it is very difficult to 

 show them in a photograph, since their colours 

 so closely resemble those of the flowers them- 

 selves.) The illustration will, I think, show 

 clearly that each little flower has put forth 

 numerous stalked stamens, or pollen-producing 

 organs, and when the bees and flies climb up 

 the hanging bunches of flowers, they become 

 dusted with fertilising pollen. By the time a fly 

 has travelled over the flowers of a well-developed 

 shoot, his natural colours are more or less ob- 

 literated by the yellow dust from the stamens. 



Now, when a spray of flowers appears, the 

 first flowers to open generally produce large 

 quantities of pollen ; in fact, they are frequently 

 devoted entirely to that purpose, and after 

 performing that function they fall away and 

 perish. Other flowers higher up the stalk, how- 

 ever, when they first open develop like those 

 shown in Fig. i6 (Plate lo), producing first a 

 central object divided at its apex, but with 

 stamens which either come to maturity later, or 

 not at all. Having now grasped these little details 

 of the floral structure, w^e shall, I think, understand 

 what part the fly, as dusty as ^' the miller of the 

 Dee," plays in the sycamore's scheme for pollin- 

 ation. 



The base of the central objects shown in Fig. 

 1 6, and previously referred to, will be seen to be 



25 



