X.] OLD DOUBLE PERENNIAL ALPINE 171 



may be readily lifted with balls at any time, and without 

 much interfering with their growth. 



By no means so common as the ordinary Wallflower, 

 but quite as useful and attractive as border plants, are 

 some of the more modern hybrids. These Wallflower-like 

 perennials are known as Erysimum. The most familiar 

 is Erysimum ochroleucum (Cheiranthus Alpinus, or the 

 Alpine Wallflower). It grows in spreading tufts, which 

 in spring and summer are covered with beautiful sulphur- 

 coloured flowers ; it thrives equally well on the rock 

 garden or in the level border, but needs to be fre- 

 quently divided. Cheiranthus Marshalli bears orange- 

 coloured blossoms, and mutabilis has variegated tints. All 

 these perennials like dry soil during winter and plenty 

 of water in summer ; they can be readily increased by 

 cuttings, taken off when the plants are going out of 

 flower. 



I have found it a good plan sometimes to make a 

 sowing of Wallflowers at the end of the summer, leaving 

 the young plants in their seed bed all winter; plant out 

 in March, and in this way secure a satisfactory supply of 

 flowers all through the following winter. 



