246 ROCK GARDENING FOR AMATEURS 



belonging to the natural order Campanulaceae, and are 

 often classed with the Campanulas under the name of 

 C. grandiflora. They are native of China and Japan. 

 For garden purposes, Platycodon is generally accepted as 

 a suitable title. Platycodon grandiflorum has handsome 

 blue flowers, and grows from 6 to 9 inches high. The best 

 for the rockwork are the Mariesii varieties ; they are 

 dwarfer, and have large and handsome flowers in blue 

 and white. These plants will thrive in common loam, 

 though preferring a little peat intermixed. They flower 

 in summer, and are hardy, but sometimes die after a 

 few years, owing to the tuberous roots rotting. They 

 are raised from seeds or increased by division. Some 

 are successful in raising them from root-cuttings. 



Polygonum (Knot-grass). Several Polygonums are 

 good rock-garden plants. They have generally rather 

 cylindrical spikes of small flowers, and belong to the 

 natural order Polygonaceae. With the exception of P. 

 sphaerostachyum, the following, which comprise the only 

 sorts worth having for the rockery, can be grown in 

 common soil. The easiest is Polygonum affine, some- 

 times called Brunonis, native of Nepaul, which is of 

 creeping habit. It has spikes of rosy-red flowers in late 

 summer and autumn, and narrow leaves which become 

 brilliantly coloured in autumn. P. vaccinifolium, from 

 the Himalayas, also blooms late ; it likes partial shade, 

 and a rather moist place, is also of creeping growth, and 

 has pretty Heath-like spikes of pink bloom. The Hima- 

 layan P. sphaerostachyum grows about 9 inches high, 



