272 ADAPl^ATIONS AMONG ALPINE PLANTS 



large number of flowers in an inflorescence, to form 

 a head, as in the Rampions or Composites. Or, 

 again, if the inflorescences become one-sided, all the 

 flowers tm-ning in one direction, as in the Bearded 

 Campanula, and many Boraginese, conspicuousness 

 is markedly increased. 



As regards scent, the odours of many flowers are 

 well known to be characteristic, such as those of the 

 Mignonette, or Jasmine. Yet other quite unrelated 

 plants often possess exactly the same kind of scent. 

 A good example is the vanilla scent, typical of the 

 fruits of a tropical climbing Vanilla Orchid, which is 

 possessed by many other flowers, among them the 

 Black Nigritella (p. 135) and the Linnaea (p. 250). 



Again, many plants possess what to us are 

 unpleasant or nauseous odours, which apparently are 

 quite acceptable to certain insects. Such flowers are 

 rare in the Alpine zone, the most unpleasant being 

 Thalictrum aquilegifolium, Linn., which has the Elder- 

 odour. 



We now turn to the *^free samples" oScred to 

 insect visitors. Pollen alone is rare, though in the 

 Alps the flowers of the Alpine Anemone (p. 87) 

 and the Narcissus-flowered Anemone (p. 41), the 

 Alpine Poppy (p. 195) and Thalictrum aquilegifoliumy 

 Linn., possess no nectar. As a rule, however, nectar 

 or honey together with pollen are the inducements 

 which entice insects to enter the flower. 



Honey is secreted by special glands known as 

 nectaries, the position and shape of which varies in 



