320 ROCK GARDENS 



found suitable and hardy. They all require a warm spot in light, 

 free loam, and can easily be propagated by seed or cuttings. 



P. caeruleus. — Grows about 9 inches high. Has glaucous, grey 

 foliage, and lovely, pale turquoise-blue flowers. It is not very 

 hardy. It comes freely from seed, but, unfortunately, frequently 

 not true, the same batch of seedlings giving many shades of colour, 

 and only a very small percentage of which will be the desired tint. 



P. azureus. — Is of branching habit, bearing numerous violet-blue 

 flowers in whorls during the summer. This plant is quite hardy. 

 P. Jeffrey anus is a variety of this, with larger flowers. 



P. glaber. — Rather dwarf, prostrate habit, with dense heads of 

 a fine shade of blue, tinged with rose. Very variable from seed. 



P. glaucus. — Forms a compact plant about 9 inches high, with 

 bluish-grey foliage and dense heads of large, purplish-blue flowers 

 in July. Rather a distinct plant. 



P. heterophyllus. — Grows from 12 to 1 8 inches, forming a graceful, 

 sub-shrubby plant. Flowers pale, violet-blue, with throat of azure- 

 blue. A lovely plant, and hardy, except in a severe winter. It, like 

 many others of the genus, varies considerably from seed. 



P. Aumz'lzs.'— Requires a sunny spot in gritty loam and leaf-mould. 

 Forms a compact tuft 8 inches high. Large flowers of a reddish- 

 purple colour in May and June. It should be watered freely during 

 the summer. 



P. procerus. — Is of creeping habit, forming neat tufts, from which 

 rise 6- to 12-inch stems, bearing dense spikes of amethyst-blue 

 flowers. One of the best of the family and the earliest to bloom. 

 Can be raised easily from seed. 



P. Scoulefi.—Ps. plant of half-shrubby habit, growing about 12 

 inches high. Flowers a pretty shade of pale purplish-blue, borne 

 in terminal racemes. A good plant, of easy culture. Propagation 

 by seed or cuttings taken in spring and struck in a little bottom 

 heat. 



Pernettya mucronata (Ericaceae) 



Dwarf-growing, evergreen shrub, growing freely in peaty loam, 

 or even in heavy soil with leaf-mould added. Flowers small and 

 pinky-white, followed in the autumn by berries about the size of a 

 large pea. There are a good many varieties of white, pink, red, 

 and purple-black berries, with all intermediate shades. A very 

 useful shrub for the higher slopes of the rock garden. Quite hardy, 

 and will grow readily under trees. Increased by division. 



Petrocallis pyrenaica (syn. Draba pyrenaica) 



A very dwarf-growing little plant for a warm spot in fine, sandy, 

 fibrous loam soil. Pieces of limestone should be buried in the soil 



