170 



BRITISH PLANTS 



Flowers are visited by any honey-seeking insect capable 

 of extracting the honey. Some of the smaller flowers 

 secrete a great deal of honey, but as it is more or less 

 freely exposed, a large number of insects are able to 

 reach it. Some of the Umbelliferae and Composite, for 

 instance, with only slightly-concealed honey, are visited 

 by an enormous number of insects e.g., dandelion and 

 Senecio Jacobcea. The hogweed (Heracleum Sphondylium) 

 is said to be visited by 118 different insects possibly a 

 record among British plants. Scabious and Jasione mon- 

 tana are also plants visited by a host of insects. In some 

 cases insect-pollination is so certain that the power of 



FIG. 69. PETAL OF BUTTER- 

 CUP WITH NECTARY (a) AT 

 BASE. 



FIG. 70. FENNEL: LONGITUDINAL 



SECTION OF FLOWER. 



a, nectary ; 6, inferior ovary ; c, stigma ; 



d, stamen ; e, petal. 



self-fertilization is said to have been lost. With the 

 increase in size and complexity of the flower, and the 

 more effective concealment of the honey, the smaller 

 insects with short tongues are excluded, and in extreme 

 cases the honey is so deep or so difficult to get at that 

 only the strongest or longest-tongued bees and Lepidop- 

 tera (butterflies and moths) can effect its extraction. 

 Lepidopterous flowers have usually long, narrow corolla- 

 tubes or spurs e.g., toadflax and red valerian. The 

 honeysuckle opens between seven and eight in the even- 

 ing, when it becomes strongly scented. The tube is 

 more than an inch long, and can only be explored by the 

 very longest-tongued moths e.g., hawk-moth. There is 



