314 ROCK GARDENS 



O. arvensis. — A dwarf-growing plant, forming dense, spreading 

 tufts about 6 inches high. Masses of pink flowers in June. Quite 

 a useful plant, and of the easiest culture. 



O. fruticosa. — Is a dwarf, shrubby species, growing about 12 

 inches high. Flowers purple, and borne in racemes during the 

 summer. 



O. Natrix. — Also a somewhat shrubby plant, growing about 18 

 inches high, with yellow flowers veined with red. 



O. rotundifolia. — A half-shrubby plant, growing 12 to 18 inches 

 high. Flowers rose-coloured, upper standard veined crimson. A 

 useful and handsome plant for the rougher parts of the rock garden. 



Onosma (Boraginaceae), Golden Drop 



A genus of plants, some of much beauty. They all require deep, 

 well-drained, sandy soil in full sun, in such a position that no wet 

 can lie about and rot them. They do well planted between rocks, 

 round which they can get their roots and keep them cool and moist. 

 As some kinds are of but little beauty or value, the following is a 

 selection of the best : — 



O. albo-roseum. — Forms a compact tuft about 6 inches high, with 

 hairy, rather silvery leaves. Flowers white, changing to pale rose, 

 borne in racemes during June and July. There is also a form 

 called alba^ in which the flowers remain white. Both are very 

 pretty, and can be propagated by cuttings in the summer. 



O. Bourgaei. — Grows about 6 inches high, forming compact tufts 

 of silvery-white leaves, and bearing deep yellow flowers in June and 

 July. 



O. tauricum (syn. O. er.hioides). — Forms compact tufts of rather 

 hairy leaves, about 6 to 8 inches high, with clear yellow, fragrant 

 flowers, borne in drooping clusters on stems about 14 inches high. 

 Can be increased by cuttings. A handsome plant for a dry ledge. 



O. Thompsoni. — Forms a tuft of rather hairy leaves. Flowers 

 red, borne in a dense head on an upright stem about 14 inches 

 high. 



Ophrys (Orchideae) 



Small terrestrial orchids, mostly too delicate and difficult to grow 

 to be of much value for the rock garden. There are, however, a 

 few native species which may be tried. 



O. apifera (Bee Orchis). — Requires a dry, warm soil of loam and 

 broken limestone, and should have the surface of the ground, in 

 which it grows, covered with cocoa fibre and sand about i inch 

 thick to keep it moist. The leaves are glaucous and lie close to the 

 ground. Flowers, borne on stems about 12 inches high, are velvety 

 brown, with yellow markings. 



