28 MOUNTAIN AND MOORLAND 



adaptations or fitnesses of mountain plants in our third 

 study. 



Near the top of the hill there were several flourish- 

 ing tufts of Thrift, or Sea Pink (Armeria vulgaris\ 

 which one is accustomed to find on rocky places near 

 the shore. It is striking to find a seashore plant on 

 the top of a mountain. It is adapted for hard condi- 

 tions a perennial with narrow leaves from which the 

 loss of water is strictly economised. Its fine rose-pink 

 tufts of flowers are very conspicuous, but there are 

 not many insects to attract up here, and, as a matter of 

 fact, the Thrift is able to dispense with their visits. 

 The styles of the flower have a way of coiling that 

 ensures their being dusted with pollen from the 

 stamens. Self-pollination will occur if insect pollina- 

 tion fails. 



It is not very clear why the Thrift should be found 

 in the extreme situations of mountain-top and sea- 

 shore rocks, and not (unless as a rarity) in the inter- 

 mediate zones. The same is true of the purple- 

 flowered, opposite-leaved Saxifrage (Saxifraga oppo- 

 sitifolia), which occurs only above 3,500 feet and at 

 sea-level. It has been suggested to me that both 

 plants flourished between the two extremes before the 

 severe glaciation of the Ice Ages, that the ice gave 

 place to vast tracts of forest and moor over the greater 

 part of the country, and that the Thrift is constitu- 

 tionally unsuited to living in either of these habitats. 

 Nowadays it is probably isolated on the hilltops by the 

 moor cordon and on the shore rocks by the surround- 

 ing zone of cultivation. 



It is interesting to notice that on a particular stretch 

 of rocky ground at no great altitude, a succession of 



