THE ALPINE TOADFLAX 115 



one season, as in the plains, and consequently some 

 different plan of operation has to be adopted, and 

 this finds its expression in the perennial habit. 



The flowers of the Alpine Toadflax, which, like 

 many other members of the same order, only possess 

 four perfect stamens, the fifth being suppressed, are 

 remarkable for the spur formed by one of the petals, 

 a rare occurrence in this family. The petals are also 

 so shaped that the corolla is closed at the throat. 

 The same feature is also seen in the Snap-Dragons 

 (Antirrhinum). The pollen and the honey are thus 

 hidden. This is a special adaptation, to ensure that 

 only large and strong insects, such as certain bees, can 

 force open the throat of the corolla. Further, such 

 insects must possess a long tongue to reach the 

 nectar secreted in the spur, and incidentally cross- 

 fertilise the flower. This flower is thus specialised for 

 certain insects alone. 



There are many other Alpine plants flourishing in 

 rocky situations, such as some of the Potentillas 

 (natural order Eosaceae) or the Eock Catchfly (Silene 

 rupestris, Linn., natural order Caryophyllacese) (Plate 

 XVI., Fig. 2), with its widely spreading branches, 

 but most of them are not known to present any very 

 striking points of biological interest. 



