Part I. RUIN AND WALL GARDENS. 35 



inducing it to naake a lingering growth. But it is interesting 

 and useful to know that by placing many of these delicate plants 

 where their roots can secure a comparatively dry and well- 

 drained medium, they remain in perfect health. My attention 

 was first called to the great adaptability of walls, ruins, &c. for 

 growing many choice rock-plants while visiting Dublin a few 

 years ago. Near Lucan, I observed the upper portion of the 

 old inclosing brick wall of a garden —indeed, all of it that was 

 out of convenient reach^covered with a dwarf, green, moss- 

 like plant, and before coming close to it, I asked the gardener 

 what it was that made the wall so green. " It is," he replied, 



Fig, 31. — ^Alpine plants established on old fort wall. 



"a plant like a moss, but every spring it is covered with the 

 most ' beauteeful ' ilowers." And " sure enough " that is its cha- 

 racter, for it proved to be the pretty little Erinus alpinus, which 

 would have had little or no chance of existing on the level ground 

 in the same place, and which had, in the old days of cultivating 

 rock-plants, escaped by seed on to the wall, and there found a 

 home as congenial as its native one. This will suggest at once 

 that many plants from latitudes a little farther south than our 

 own, and from alpine regions, may find on walls, rqcks, and 

 ruins that dwarf, ripe, sturdy growth, stony firmness of root 

 medium, and dryness in winter, which go to form the very con- 

 ditions that will grow them in a climate entirely different from 

 their own. There are many alpine plants now usually seen culti- 

 vated in frames, even in places where there is a fine collection 



