102 



THE BOOK OF NATURE STUDY 



flower, as was stated above, is a shoot specially modified for the 

 purpose of sexual reproduction. 



Once the need of pollination has been recognised we are in 

 a position to consider the use of the brightly coloured petals and 

 the nectar in the flower. The uses of the other parts will have 

 been already realised ; the sepals serve to enclose and protect 

 the other parts of the flower in the bud, while the stamens form 

 the pollen, and the carpels enclose and protect the ovules. Why 

 has the Buttercup, like so many other flowers, an apparently 

 useless display of brightly coloured petals ? 



Since the stamens and carpels are close together in the same 

 flower it might have been expected that the pollen would fall 

 directly on the stigmas. This is, however, comparatively rarely 

 the case, and many of the features of flowers are to be explained 

 as rendering likely the carriage of pollen from the stamens of 

 one flower to the stigma of another. Sometimes this cross- 

 pollination is effected by the wind, but in the case of most con- 

 spicuous flowers the pollen is carried from flower to flower by 

 the insects visiting them in search of food. Everyone knows the 

 way in which bees, butterflies, flies, and other insects visit flowers, 

 and has probably realised that they get honey and pollen from 

 them. The insects may feed off the nectar or pollen, or they 

 may in the case of bees carry it home to be stored, or to feed 

 their young. In visiting the flower the insect gets some part 

 of its body dusted with pollen, and on going to another flower 

 of the same kind may rub this on the stigma, and so pollinate 

 the flower. The variety in form and colour of flowers finds its 

 explanation in the complicated and beautiful adaptations which 

 exist between the flower and its insect visitors. These will be 

 pointed out in each example described. 



The Buttercup has a relatively simple method of pollination. 

 Many insects, especially flies, visit the flower, the bright colour 

 of which makes it conspicuous from a distance. They may 

 either feed off the pollen, of which a large quantity is formed in 

 the numerous stamens, or may suck the nectar from the little 

 pocket-like nectaries at the base of each petal. The provision 

 of this food is not an indiscriminate charity to the insects on 

 the part of the plant. While feeding, the insect visitors get 



