ALPINE PLANTS IN THEIE NATIVE HAUNTS. 



77- 



contribue k I'^paississement de la feuille, du tissu en palissade, de la 

 cuticule et a I'augmentation des fibres. C'est ^galement k la s^cheresse 

 de i'air qu'il faut attribuer I'abondance des poils chez les plantes 

 alpines. 



" L'eclairement intense et la secheresse de I'air suffisent done h ex- 

 pliquer tous les caracteres des plantes alpines, sauf la faible longueur, 

 des tiges et des entrenoeuds, et le faible d^veloppement du bois. Mais 

 nous avons vu que des derniers caracteres sont ceux qui d^terminent les 

 alternances d'une temperature elevee avec une temperature froide. Or. 

 nous Savons que, sur les montagnes, les journees d'et^, relativement 

 chaudes, succedent k des nuits tres froides ; c'est done la qu'il faut 

 chercher la cause de la faible longueur des tiges et de la reduction des 

 bois. ... On voit done, en somme, que tous les caracteres de la vegeta- 

 tion alpine sont determines directement par les conditions exterieures 

 dont 1 'ensemble constitue le climat alpin, et dont les principales sont: 

 l'eclairement intense; I'air sec, le sol humide et les alternances de tem- 

 perature."* 



I have purposely left to the end the consideration of the much- 

 debated question of the colour of alpine flowers. Nothing more appeals 

 to and charms the alpine traveller who for the first time sees the 

 meadows and pastures in their full summer glory than the wonderful 

 brilliancy of the floral tints. It would be particularly satisfactory if 

 some explanation were forthcoming to account for the more vivid 

 colours of the alpine flora. Unfortunately, the problem at present lies 

 mainly in the realm of conjecture and speculation. I have, myself, 

 had many opportunities of observing the intense floral colouring of 

 alpine specimens when compared with one of the same species grown in 

 lowlands. The common willow herb, Eyilobium angustifolium, grows 

 almost as freely at Saas Fee in the Canton Valais at an altitude of 

 5500 feet, as it does in my own garden at Chislehurst, where it is occa- , 

 sionally allowed to exist as a rather attractive, if somewhat exuberant, 

 weed. It is, as we should expect, not so tall at Saas Fee, but its colour, 

 is much more brilliant. Again, I had for many years grown Aquilegia 

 pyrenaica in my rockery, but I never realized what a beautiful flower 

 it really was until I found it by the roadside, close to the Col de Portalet 

 in the Pyrenees, at an altitude of about 7500 feet. The colour just 

 made all the difference. Keener and Bonnier have both remarked on 

 the brilliancy of floral colouring of their alpine cultures of lowland 

 plants, and Kerner has pointed out that the flowers of some species, 

 which were pure white when cultivated in his control garden in Vienna, 

 produced petals tinged with pink when cultivated in the alpine garden 

 on the summit of the Blaser. He attributes this to a suffusion of antho- 

 cyanin, and suggests the same cause as the explanation of the brilliancy 

 of floral colouring of many plants growing at high altitudes.! Sachs 



* Leclerc du Sablon, op. cit. p. 489. 

 t Kerner, op. cit. vol. xi. p. 551. 



