ROCK AND ALPINE PLANTS 139 



now covers quite a square yard of ground 

 surface. An excellent shrub for town plant- 

 ing is Genista sagittalis, which to my know- 

 ledge has grown and flowered freely on 

 a rockwork in the centre of London for the 

 past ten years. Another excellent Alpine is 

 the Prophet Flower (Arnebia echioides), which 

 for many years has charmed us with its 

 curious yellow flowers, the black marking of 

 which gradually gives way with age and from 

 which the popular name of the plant was 

 given. Several species of Campanula actually 

 revel in the town atmosphere, notably our 

 native C. Trachelium and C. rapunculus, both 

 of which may be seen in various parts of 

 London running about rampant and flowering 

 profusely. Of the more showy flowered kinds, 

 the most notable for surviving where the air is 

 chemically impure are C. carpatica, in variety, 

 C. persicifolia (various varieties), C. turbin- 

 ata, C. lactiflora, C. punctata, and C. rotundi- 

 folia, a patch of the latter having flowered 

 annually in a town garden for the past eight 

 years. Two other desirable kinds are G. F . 



