136 



INTRODUCTION 



Veronica Chamaedrys will serve as a typical example. The bright blue flowers 

 are streaked with darker lines, and ornamented in the middle with a paler nectar- 

 guide. They are united into moderately conspicuous inflorescences, and are 

 homogamous. The style with its terminal stigma projects obliquely downwards 



Fig. 51. Veronica latifolia^L., a Hover-fly Flower. A. Flower seen exactly from the front (x 7), 

 B. The same seen from the side, after half of it has been removed (X 7); j, sepals ;/, petals ; »;, nectary; 

 «, stamens ; J/, stigma. 



out of the middle of the flower where nectar is produced, while the two stamens 

 diverge from each other to right and left. The filaments are narrowed at their 

 bases and can therefore be easily turned inwards. Small variegated Syrphidae 



(Ascia podagrica, Melanostoma mellina, and 

 others) first hover for a second in front of the 

 flower, delighting in its beautiful colour, and 

 then settle on its centre, thus coming into 

 contact with the projecting stigma. In order 

 to obtain a firm hold, they first grasp the 

 filaments with their fore-legs, and immediately 

 afterwards with their middle and hind-legs, 

 and before one has time to see it they have 

 unconsciously brought together the two stamens 

 under the ventral side of the abdomen, and 

 dusted that region with pollen, which is de- 

 posited on the stigma of the next flower the) 

 visit (Fig. 50). 



This striking floral mechanism also occurs 



in a few other species of the genus Veronica, 



though in some of them it is not so highly 



perfected, e.g. V. longifolia, montana, latifolia 



(=urticifolia). (See Fig. 51.) 



Our native species of Circaea present the same adaptation to hover-flies, for 



it is only insects of this kind that bring their floral mechanism into action in the 



proper way. 



Fig. 52. Circaea hitetiana, /-., a Hover-fly 

 Flower. The flower is seen obliquely from above. 

 a, ovary ; 5, sepals ; c, petals ; d^ stamens ; e, style 

 with stigma. 



