PLANTS FOR ROCKERIES. 



103 



N. triandrus (angels' tears), wliite, N. Johnstoni, 

 Queen of Spain, yellow, are charming forms suit- 

 able for rockwork, in clamp shaded positions. 



NiEKEMBERGiA (Cup-flower). — jST. rivularis (brook-lov- 

 ing), La Plata ; trailing ; flowers white : July. Posi- 

 tion shady and moist ; loamy soil. Division. 



Ojiphalodes verna (spring). — South Europe ; height 

 6 inches, creeping ; flowers blue, with white throat : 

 March to Slay. Position rough part of rockery ; 

 common soil. Runners or division. 



Onosma (Golden Drop).— 0. tauricum (Taurian) ; height 

 6 to 8 inches ; flowers yellow : summer. Sunny 

 position ; sandy loam. Cuttings under glass in 

 summer. 



Oxalis (Wood Sorrel). — 0. Bowiei (Bowie's), Cape of 

 Good Hope ; height 6 to 10 inches ; flowers rose- 

 red : August. Sunny slopes ; sandy loam. Divi- 

 sions. 0. floribunda (bundle-flowered), synonym 

 0. rosea, Chili ; height 6 to 12 inches ; flowers 

 rose : spring. Fronts of rockery ; common soil. 

 Division and seeds. 



Papaver (Poppy). — P. alpinum (alpine), Alps of 

 Europe ; height 6 inches ; flowers yellow, rose- 

 tinted, or white : summer. Position exposed ; 

 common soil. Division and seeds. P. nudicaule 

 (naked stemmed), Iceland Poppy, Siberia ; height 

 8 to 15 inches ; flowers bright orange, yellow, or 

 white : summer. Sunny position ; common soil. 

 Division and seeds. 



Phlox. — P. divaricata (spreading), North America ; 

 height 9 to 16 inches ; flowers pale lilac or bluish : 

 spring and early summer. Position sunny and 

 open; good soil. Division. P. nivalis (snowy), 

 South New York ; trailing ; flowers pink ; and 

 subulata Nelsoni, a hybrid form : April. Position 

 where it can trail over rocks ; common soil. 

 Division. 



PoTENTiLLA (Cinque-foil.— P. alba (white), European 

 Alps ; procumbent ; flowers white : February to 

 August. P. alpestris (mountain), Britain ; height 

 6 to 12 inches ; flowers bright yellow : July. P. 

 nitida (shining). South of Europe ; height 2 inches ; 

 flowers delicate rose : summer. P. pyrenaica 

 (Pyrenean), Central and Southern Pyrenees ; height 

 8 to 16 inches ; flowers deep golden yellow : sum- 

 mer. All the species succeed well in cool open 

 positions ; common soil. Division. 



Primula (Primrose). — A large and popular family. 

 P. auricula (common auricula), European Alps ; 

 height 3 to 4 inches ; flowers various, normally 

 yellow : spring. Position cool ; sandy loam and 

 leaf soil. Division and seeds. [See Alpine Auri- 

 culas.] P. cortusoides (cortusa-like), Siberia ; 



height 6 to 10 inches ; flowers deep rose : early 

 summer. P. c. amccna is a garden variety. Posi- 

 tion sheltered, sunny nook ; soil light and rich. 

 Division and seeds. P. denticulata (toothed), 

 Himalayas; height 8 to 12 inches ; flowers bright 

 lilac: spring and early summer. Position sheltered 

 and sunny ; deep rich loam. Division or seeds. 



Fig. 55. Peimxjla Scotica. 



P. erosa (bitter), Himalayas ; height 4 to 8 inches ; 

 flowers lavender or purple : early spring. Position 

 sunny and sheltered ; sandy loam or leaf soil. 

 Division and seeds. P. farinosa (mealy), Northern 

 and Central Europe ; height 3 to 10 inches; flowers 

 light purple with yellow eye : early summer. Posi- 

 tion cool and partially shaded ; rich loam. Division 

 and seed. P. glutinosa (glutinous), South Europe ; 



