NEW AND BEAUTIFUL ROCK PLANTS 99 



not only valuable for the beautiful shades of blue which 

 they give, but also because they will thrive on poor 

 soil in dry places. They are, of course, summer bloomers. 



CARDAMINE TRIFOLIATA. This pretty sister of 

 the Lady's-smock, with its white flowers in early spring, 

 is worth a place in the bog garden. 



CELMISIA HOLOSERICEA. A most beautiful plant, 

 too little known. It bears large flowers with a yellow 

 centre. It should be covered with a square of glass in 

 winter. Coriacea is another good Celmisia. 



CHEIRANTHUS (WALLFLOWER). The common 

 Wallflower creates a sympathetic feeling towards the 

 members of its genus, but in the case of Allionii it needs 

 no adventitious aid, for it is a beautiful plant growing 

 about a foot high, of erect habit, and well suited either 

 for the border or rockery. It bears its warm orange- 

 yellow flowers in great profusion, and over a long period 

 in good soil. On dry limestone it is not so much at home 

 as its sister the Wallflower. I think this is a better plant 

 than either C. Alpinus or C. Marshalli, both of which are 

 used for the rockery. C. Allioni seeds itself freely. 

 There is another plant in commerce under the name of 

 Allioni ; it is less neat in habit and paler in colour ; 

 probably it is a form of Alpinus. A hybrid between 

 mutabilis, an old species with purple and yellow flowers, 

 and Allioni has been raised ; it has flowers of a warm, 

 bronzy orange. 



CHRYSOGONUM VIRGINIANUM. A useful plant for 

 summer blooming, with showy yellow flowers on stems 

 nine inches high. It likes a cool, shady spot. 



CISTUSES. All the Cistuses may be used in the rock 

 garden if space permits. See~notes~in chapter iv. 



