ALPINE PLANTS AND THEIR TREATMENT. 



117 



sights of the vegetable kingdom; no language can describe them, 

 no pencil reproduce them ; they are the jewels of the Creator 

 and His favoured ones in the world of plants, and both they and 

 their marvellous surroundings alike enchant and astonish us. 



But not only are their flowers peculiar, but the leaves also of 

 plants on high elevations are differently constructed to those of 

 the plains. The powerful action of the sun impresses a distinc- 

 tive character not only on the exterior form, but even on the very 

 organisation of Alpine plants. The leaves are thick and of com- 

 pact texture, and, thanks to the density of their skin, they are 

 capable of resisting the drying influence to which they are 

 exposed from the intensity of the sun's heat. Often, too, they 

 are further protected from this drying influence by a thick 

 pubescence, almost always composed of starry hairs which pro- 

 tect the skin — the grey down which, like thick felt, covers other 

 Alpine plants, especially the Composite (Edelweiss, Senecio, 

 Artemisia, Achillea nana), serves the same end. And it has been 

 repeatedly noticed that in positions exposed to the sun on open 

 heights and slopes almost all plants have coriaceous leaves or a 

 close pubescence, whilst in shaded and sheltered ravines, and in 

 the gorges and hollows which serve as beds for the torrents, they 

 possess greener and more delicate leaves. 



The anatomy of Alpine plants proves that the cells of their 

 leaves are smaller, and that they have thicker walls and more 

 concentrated contents than plants of the plains, so that in alter- 

 nate freezing and thawing the tissues are not torn even at tem- 

 peratures at which the plants of the plains, whose cells are 

 provided with thinner walls and contain a greater proportion of 

 water, would infallibly succumb. The more tufted habit, and 

 the imbricated leaves of the mountain plants also contribute to 

 protect them from the cold air currents which pass over the 

 surface of the ground. 



And it is precisely these frosts, renewed as they are every 

 night, that explain the cause of the dwarfness of all these plants. 

 The most recent physiological researches have proved that it is 

 during the night that plants grow the most rapidly. By day 

 they grow so much the less the more they are exposed to the 

 sun. For plants of the high Alps there is very little opportunity 

 of nocturnal growth, which is prevented by the frosts. It is only 

 during those hours of the day when the sun is strong enou gh to 



