248 ROCK GARDENS 



C. polyrhiza. — Moist peat and loam in half shade. Dwarf-grow- 

 ing, with spikes of incurved and spotted canary-yellow flowers in 

 July, borne in profusion. Quite hardy, and a good plant. 



C. violacea, — Sheltered position in sandy loam. A shrubby 

 plant, growing 18 inches to 2 feet, with pale blue flowers, spotted 

 violet. Is hardy only in favourable localities. Easily increased by 

 division, A lovely plant, and well worth giving protection to during 

 the winter. 



Callirhoe (Malvaceae), Poppy Mallow 



Dwarf plants of the Mallow tribe. 



C. involucrata. — Hot, dry position in very light sandy loam. 

 Grows about 6 inches high, with trailing stems, cut leaves, and 

 crimson-magenta-purple flowers, rather like a Mallow. Blooms 

 in June. Easily raised from seed. Colour of the flowers is 

 brilliant, but merging on the magenta shade, so care should be 

 taken with what flowers they are associated. 



Caltha (Ranunculaceae), Marsh Marigold 



Lovely and showy plants for the waterside. The single form, 

 though lovely, is so common that it is hardly worth while giving 

 it a place, but there are some very good double forms which should 

 be grown. All are of easy culture. 



C. biflora. — Compact grower, with white flowers. 



C. 7nonstrosa^fi. pi. — A fine double form. 



C. palustris^ fl. pi. — A double form of the common Marsh 

 Marigold. 



C. polypetiila. — Large leaves and yellow flowers. 



C. polysepala. — Enormous leaves and flowers, said to have been 

 obtained from the Vatican. 



C. purpiirascens. — Rather distinct species, with purplish stems 

 and the outside of bright orange-coloured flowers of a purplish 

 tinge. 



C. parnassi folia. — Yellow flowers in April and May. 



Campanula (Campanulaceae), Bell-flowers 



A large genus varying greatly in habit, height, and colour. 

 Many are too coarse and tall-growing for the rock garden, but 

 amongst the dwarfer-habited kinds will be found some of the 

 choicest plants for the garden. They mostly like a sunny aspect 

 and sandy loam, and are all very partial to limestone, except 

 Alliomi^ pulla, and pulloides^ which all three dislike extremely. 

 There are so many varieties and hybrids, some scarcely dis- 



