160 tTHE STORY OF THE PLANTS. 



supernumerary and useless petals ; while in a 

 composite it is a flower-head in which the central 

 florets have been converted into barren ray-florets. 

 In either case, however, the result is the same — 

 the flowers are rendered abortive and sterile. 



Nature's way is quite different. Here is how 

 she manages the fertilisation of one of these ray- 

 bearing composites — say for example the sun- 

 flower, where the individual florets are quite big 

 enough to enable one to follow the process with 

 the naked eye. The large yellow rays act as 

 advertisements ; the bee, attracted by them, 

 settles on the outer edge and fertilises the 

 flowers from without inward. To meet this 

 habit of his, the florets of the sunflower pass 

 through four regular stages. They open from 

 without inward. In the centre are unopened 

 buds. Next come open flowers, in which the 

 stamens are shedding their pollen, while the 

 stigmas are still hidden within the tube. Third 

 in order, we get florets in which the stamens 

 have withered, while the stigmas have now 

 ripened and opened. Last of all, we get, next 

 to the rays, a set of overblown floreto, engaged 

 in maturing their fertilised fruits. The bee thus 

 comes first to the florets in the female stage, 

 which he fertilises with pollen from the last 

 plant he visited; he then goes on to florets in 

 the male stage, v/here he collects more pollen 

 for the next plant to which he chooses to devote 

 his attention. The florets of the sunflower are 

 interesting also for the fact that, unlike most 

 composites, ihey still retain obvious traces of 

 a true calyx. 



