ALPINE PLANTS IN THEIR NATIVE HAUNTS. 



73 



rather is that Bonnier 's laboratory experiments have gone to show that 

 there are other factors present in the alpine climate which will produce 

 effects in vegetation somewhat similar to those caused by brilliant illu- 

 mination. By growing in Paris plants of the same species, some of 

 which were cultivated under normal conditions, and others which during 

 the summer were by night subjected to an artificially created low tem- 

 perature, Bonnier succeeded in checking in the latter the growth in 

 length of stem, and in producing in these specimens, when compared with 

 the former, leaves which were thicker but of smaller area (fig. 50). He 

 also noted in the plants which were subject to the alternation of high and 

 low temperature an increase in the intensity of floral colouring, com- 

 bined with an increase of the size of the flower. The plants were also of 

 a more vivid green, owing to a more profuse production of chlorophyll.* 

 In certain cases the red colouring matter which can be observed in the 

 foliage of plants growing at high altitudes, and to which has been given 

 the name of " anthocyanin," made its appearance in the leaves and 

 stems of the plants subjected to treatment. Not only has he subjected 

 plants to an artificially created alpine climate, but he established a 

 laboratory in the basement of an electric light station in Paris, and there 

 he proceeded by means of a continuous weak illumination, and by an 

 artificially created low temperature, to reproduce Arctic conditions.! To 

 these conditions he subjected specmiens of Saxifraga oppositifolia and 

 Silene acaulis, which he collected in the Alps before they were un- 

 covered by the snow, with the result that he produced in these speci- 

 mens the same characteristics which these plants exhibit when growing 

 in Spitzbergen. Bonnier 's experiments admirably illustrate the very 

 subtle, yet very powerful influence of varying conditions of illumination 

 and climate upon vegetation. Although there is frequently some diffi- 

 culty in ascertaining to which factor in the prevailing conditions a 

 modification in the form of vegetation is to be attributed, we cannot 

 fail to be struck by the fact that in the case of the alpine climate all 

 conditions tend in the direction of exercising a dwarfing influence upon 

 plant life. We have the violent storms, the snow pressure, the rela- 

 tively higher temperature of the soil when compared with that of the 

 air, the intensity of the alpine light, and, lastly, the increased radiation 

 of heat, and the consequent rapid alternation of extremes of temperature 

 for day and night. Authorities may differ as to the relative importance 

 of these factors in their effect upon plant life in alpine regions, but if we 

 take each separately as a contributing cause we have ample to explain 

 the phenomenon presented by the dwarf habit of alpine vegetation. 



Most cultivators of alpines who have tried the experiment of trans- 

 planting specimens from the Alps to English gardens, have observed 

 the modifications which these plants undergo. Edelweiss when culti- 

 vated in England grows taller, its leaves are larger, and it loses much 

 of that silvery appearance which is its distinctive charm. Silene 

 acaulis no longer appears as a close compact green cushion which it 



* Bonnier, Le Monde Vegdtal, p. 342. 

 t Bonnier, oj). cit. p. 344. 



