Part I. THE ROCK-GARDEN. 3 



tions against a flat rock, and some of the largest more than a 

 yard long. 



We think it rapacious of the Ash, a towering forest tree, to 

 send its roots under our garden walls and rob the soil therein, 

 and are surprised at finding the roots of a tree more than loo feet 

 high descending a fifth or sixth of that distance into the ground ; 

 but here is an instance of a plant one inch high penetrating into 

 the earth forty times more than it ventures into the alpine air ! 

 And there need be no doubt whatever that even smaller plants 

 descend quite as deep, or even deeper, though it is rare to find 

 the texture and position of the rock such as will admit of tracing 

 them. It is true you occasionally find hollows in fields of flat 

 rock, into which moss and leaves have gathered for ages, and 

 where, in a sort of basin, without an outlet of any kind in the ' 

 hard mountain, shrubs and plants grow freely enough ; but in 

 exceptional droughts they are just as liable to suffer from want 

 of water as in our plains. On level spots of ground in the Alps 

 the earth is often of great depth, and if it be not all earth in 

 the common sense of the word, it is more suitable to the plants 

 than what we commonly understand by that term. Stones of 

 all sizes broken up with the soil, and sand, and grit, greatly tend 

 to prevent evaporation ; the roots lap round them and follow them 

 deeply down. While in such positions, they never suffer from 

 want of food and moisture, or vicissitudes at the root. Stone, 

 it need scarcely be remarked, is a great preventer of evapora- 

 tion, and shattered stone forms the dust as well as the subsoil of 

 the mountain flanks where the rarest alpine plants abound. It' 

 should also be taken into account that the degradation so con- 

 tinually effected by melting snow water and heavy rains in summer 

 serves to earth up, so to speak, many alpine plants. I have 

 torn up tufts of them showing this in so marked a manner that 

 the remains of many generations of the old plants were seen 

 buried and half buried in the soil beneath their descendants. 

 This would, of course, be effected to some extent by the decay- 

 ing of the plants themselves, but very frequently grit and peat is 

 washed down plentifully among them, and where it does not 

 come so thickly as to overwhelm them completely, they thrive 

 with unusual luxuriance. 



Now, if we consider how dry even our English air becomes in 

 summer, and that no positions in our gardens afford such moist 

 and cool rooting places as those described, the necessity of 



