Fig. 190. Two plants of a rock-rose {Ilelianthemvm), showing the effect of low 

 ground and alpine conditions. Tlie low-ground plant {a) shows an open habit, 

 and elongated stems with comparatively large and well-separated leaves. The 

 same plant in alpine conditions is drawn to the same scale in i, and magnified in 

 c, the very short and compact habit benig in striking contrast with that of the low- 

 ground form. — After Bonnier. 



