Variety Important in Rock-building 19 



for some particular type of vegetation. It may be a 

 dryish place and sunny withal, suited to Opuntia, or the 

 Cob-web Houseleek (Sempervivum arachnoideum). 

 Or it may be a high-up rocky ledge where Saxifraga 

 cotyledon in any form would find a congenial home ; or 

 a sunnier ledge, sub-vertical wall, or sharply sloping 

 bank, somewhat lower down, where the great Pyrenean 

 Rockfoil (S. longifolia) might fittingly congregate. 

 Anon, he may be dealing with a more spacious area 

 better suited to alpine Phlox, Polygonum affine, or 

 Saxifragas apiculata or sanct&v For so distinct a trail- 

 ing subject as Polygonum vaccinifolium the face of a 

 nearly vertical rock would have to be found, while for 

 such notable groups as Haberlea and Ramondia moist 

 shady ravines, or shady, nearly vertical, moisture-laden 

 walls would have to be commissioned. These, how- 

 ever, are types for which allotted places and conditions 

 are essential. Between them comes a great alpine 

 host — the rank and file of an army thousands strong — 

 whose requirements are less fastidious. The miniature 

 growing Androsaces, such as pyrenaica, villosa, 

 chamasjasme and others that bejewel the face of the 

 rock in Nature, will be at home in chink or crevice, 

 while the trailing, profuse-flowering A. lanuginosa 

 might be given a few yards of space to fill with its 

 silvery trails and pink-flowered tresses. 



Avoid in rock-building continuous repetitions; 

 diversify in some form or another the higher rock from 

 that immediately below. Avoid, too, the stone wall 

 arrangement. Don't let the base of a rock expose to 

 view an ugly space. The base of a rock should be at 

 least half buried from view. Be very sure, should it be 

 necessary to arrange two pieces of rock one above the 

 other, that no vacuum is allowed to exist. Such things 

 must for ever remain ungarnished, inert, and an eye- 

 sore. Above all things, never employ stratified rock 

 other than in its true form (see Fig. 3). To up-end a 

 stratified rock is to ignore the best teachings of Nature, 

 an offence alike to the good gardener and geologist. 



