42 ROCK AND WATER GARDENS 



Petrocallis. Rock Beauty. On small sunny ledges 

 in good soil this is a gem. P. pyrenaica bears a pro- 

 fusion of sweetly-scented, lilac flowers on dense tufts 

 of foliage. Seed. 



Phlox. Of these the Moss Pink (P. subulata), errone- 

 ously known as P. setacea, is a dainty little evergreen 

 with rosy flowers. It is of prostrate habit, rambling 

 freely over stones and garlanding ledges. P. setacea is 

 equally delightful, with soft pink flowers ; it may be 

 massed with its sub-variety P. s. violacea, whose deeper 

 crimson flowers afford a pretty combination. 



Polygonum. Knotweed. The Himalayan variety P. 

 aflfine is a good plant for moist places, its spikes of rosy 

 red flowers producing a delightful effect. The foliage 

 is brilliantly coloured in autumn. P. vaccinifolium is 

 best in rough, rocky places where it can ramble at will 

 among stones and boulders. 



Potentilla. Cinquefoil. Plants of easy culture, thriving 

 in exposed places in loamy soil. The best of the dwarf 

 Alpines are P. nitida (Shiny Cinquefoil), with silvery 

 leaves and rosy flowers : P. alpestris (Alpine Cinquefoil), 

 much larger, with bright yellow blossoms ; and P. alba 

 ("White Cinquefoil), a dwarf variety, bearing white and 

 orange flowers. 



Primula. Primrose. One of the largest and best of 

 all the rock plant families. For rock gardens the follow- 

 ing should be grown : P. denticulata, P. farinosa, P. rosea, 

 and P. Sieboldi. Described elsewhere. 



Pyrola. Winter-green. Beautiful plants for half-shade. 

 P. rotundifolia, with tall stems and drooping racemes of 

 numerous white flowers, should be grown together with 

 its sub-variety P. r. arenaria. The flowers are sweetly 

 scented. Light sandy soil. 



Ranunculus. Crowfoot Buttercup. Of simple culture, 

 the Buttercups thrive in any fairly moist sandy soil. 

 R. alpestris, with deep glossy foliage, and large pure 



