FIFTY BEST ROCK PLANTS 321 



easily raised from seed, especially if sown wlien fresh 

 or from cuttings taken in spring. All the Aethionemas 

 like lime and a poor soil. Another excellent plant 

 for the same kind of position is Onosma tauricum 

 (Golden Drop). In a dry place and poor soil this 

 grows to a considerable size, and flowers all the sum- 

 mer. Its chief need is protection from stagnant mois- 

 ture in the winter. It should be increased by cuttings 

 taken either in April or the autumn. The cuttings 

 must be kept as dry as possible, as they are apt to 

 damp off. The Erodiums are all plants for dry places, 

 except the beautiful little E. Reichardii, which is not 

 very hardy. The best of them, perhaps, is E. gut- 

 tatum, neat in habit and with delicate white spotted 

 flowers. It is a very easy plant for sunny rock work 

 and often ripens seed in England. Geranium argen- 

 teum is the best of the Cranesbills for the rock garden, 

 more beautiful than G. cinereum because of its silvery 

 leaves. It should be planted in a deep crevice between 

 rocks looking full south, and must be top-dressed or 

 replanted if it grows out of the ground. It shares 

 this habit with many of the Alpine primulas, among 

 which it is difficult to make a choice. But certainly 

 none is more easy or beautiful than the white Primula 

 nivalis (the true name of which appears to be P. 

 pubescens alba). This thrives in any cool place in 

 light rich soil, which should be 2 ft. deep at least. 

 All the Alpine primulas like to be surrounded with 

 stones. 

 Few Gentians are quite easy, and not long ago 



