TREES FOR THE ROCK GARDEN 135 



white, crimson-spotted C. lusitanicus, the pink-flowered 

 C. villosus, the bright-red C. crispus, and the pure 

 white C. florentinus, which are quite happy in sheltered 

 rock walks especially by the sea ; they have been 

 also grown with success in many colder situations 

 inland. The Cistineae, at best, are somewhat short- 

 lived, and lose vigour and power of resistance as 

 they grow older. Keep up, therefore, young, thrifty 

 stock by yearly cuttings to fill up inevitable gaps, 

 which is a matter of no cultural difficulty. Where 

 Rock Roses are out of the question, their place may 

 worthily be filled by the hardier shrubby Helian- 

 themums, though they differ greatly from Cistineae 

 in their trailing habit and smaller flowers. The 

 breadths of brilliant colour given by these Sun Roses 

 while in bloom are invaluable, and may be enjoyed 

 to the full in almost any locality, while the many 

 variations of tint, from deep green to ashen grey, in 

 their leafage should also be taken into consideration, 

 as it increases their usefulness when out of flower. 



No list of good shrubs for the Rock Garden would 

 be complete without some reference to Yuccas, which 

 for all practical purposes must be included under 

 that head. Groups of these magnificent plants, with 

 their sub-tropical effect, cannot be surpassed for 

 nobility of outline and stateliness of flower. To do 

 them full justice, they must have space to develop 

 their grand proportions, but this may often be found 

 on the ridge or upper slope, even in rock-work of 

 limited character. Y. gloriosa, with its fine form, 

 Y. recurva, and the stemless Y. flaccida, of smaller 



