120 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Spring in the upper zones is retarded three or four months later 

 than in the lowlands ; or rather it may be said that spring does 

 not exist there at all. Immediately after the melting of the 

 snow Alpine vegetation enjoys all the advantages of summer 

 without having to pass through an intermediate season. The 

 time of the disappearance of the snow in high regions is 

 generally put at that of the longest days of the year — May and 

 June — and in a few days, almost hours, you may see the snow- 

 fields transformed into verdant pastures jewelled with flowers. 

 After seven or eight months of sleep the plants find themselves 

 suddenly surrounded with the most favourable conditions for 

 growth and development. Light, warmth, and moisture con- 

 tribute all together and at the same time to accomplish this 

 work, which is only interrupted by cold and short nights. A 

 very large amount of light is necessary for Alpines if you wish to 

 obtain a profusion of flowers. As a general rule, all the plants 

 of the Alps, far from fearing the sun's rays, absolutely require 

 full exposure to the light, and it is only since I have kept them 

 fully exposed to the sun that I have been successful with such 

 as Eritrichium nanum, Audrosace pubescens, A. helvetica^ 

 A.imbricata, A. glacialis, Edraianthus, &c. 



But if warmth and light are necessary, there is also a third 

 condition which is indispensable, and ought never to be allowed 

 to be lacking in cultivation. The rays of the sun would soon 

 destroy these delicate organs and slender flowers if there were not 

 a protecting agent to prevent the damage. This agent is water 

 diffused in the air in the form of vapour, which surrounds the 

 plants as with light gauze, thus preventing the rays of the sun 

 from scorching them. When summer comes the Alpine pastures 

 are watered by the melting snow, and the spongy soil holds the 

 moisture for a long time and gives it up to the atmosphere as 

 soon as it begins to get dry ; and in districts overtopped by more 

 elevated summits the snow which melts throughout the summer 

 on the heights supplies the Alpine and sub-Alpine regions below 

 with the necessary water. And besides, when it does not rain, 

 the nights in summer always yield heavy dews, of which the 

 effect la evident, filling the air with moisture. Later on, in the 

 months of August and September, the air is drier and the morn- 

 ing dews less heavy. It is then that the ripening of the seed 

 takes place, for which a too great moisture would be injurious. 



