362 



HUTCHINSON'S POPULAR BOTANY 



to by Kerner, is an admirable contrivance for keeping out small wingless 

 insects. 



We have seen how perfectly the flowers of Antirrhinum and Toadflax 

 are adapted for the exclusion of certain intruders, and many equally perfect 



adaptations of 

 corolla and calyx 

 might be enumer- 

 ated, where the same 

 end is to be gained. 

 In a number of in- 

 stances, the corolla 

 " forms a narrow 

 tube, still further 

 protected by the 

 presence of hairs, 

 sometimes scattered, 

 sometimes, as in the 

 White Dead-nettle, 

 forming a row. In 

 others the tube itself 

 is so narrow that 

 even an ant could 

 not force its way 

 down : while in some 

 of the Gentians the 

 opening of the tube 

 is protected by the 

 swollen head of the 

 pistil. ... In Clover 

 1 Trifolium), Birds- 

 foot Trefoil (Lotus), 

 and many other 

 LeguminossB, the 

 ovary and the 

 stamens, which cling 

 round the ovary in 

 a closely fitting tube, 

 fill up almost the 

 whole space between 

 the petals, leaving only a very narrow tube. In still more numerous 

 species the access of ants and other creeping insects is prevented by the 

 presence of spines or hairs, which constitute a veritable cheval de frise. 

 Often these hairs are placed on the flowers themselves, as in some Verbenas 

 and Gentians. Occasionally the whole plant is more or less hairy : and it 



Photo fry] [B. Step. 



FIG. 444. MARSH MARIGOLD (Caltha palustris). 



A splendid Buttercup whose brilliance is due to the golden sepals, t!ie 



petals being absent. 



