100 ROCK PLANTS OF THE PASTURES 



and Mountain House-leeks — as typical of the genus in 

 the Alps, and study them in regard to their adapta- 

 tions to the particular conditions under which they 

 there live. When the seed germinates on the primi- 

 tive soil of some freshly exposed rock, a little rosette 

 of leaves is first formed. The next step is the 

 formation of a colony of such rosettes. This is done 

 by means of v^hat are termed runners and offsets, 

 quite like those of our ordinary garden Strawberry 

 Plants. From the parent plant, in the axil of one of 

 the leaves of the rosette, a thin, prostrate stem is put 

 out, which grows for some little distance along the 

 surface of the rock. At or near its end, a second 

 rosette of leaves is formed, which in turn produces 

 other runners and off*sets. 



If we remove from the soil a colony of Semper- 

 vivum such as that of the Mountain House -leek 

 figured on Plate XXIV., Fig. 1, we shall have no 

 difficulty in making out the runners and their off- 

 sets. In most cases where these plants grow on 

 flat-topped rocks with plenty of room all round, the 

 runners are very short and new rosettes or buds are 

 formed close to the parent, and so a very compact 

 colony is produced. It is thus scarcely possible, 

 unless the plant is removed from the soil, to make 

 out the relationships of the colony. The runners 

 connecting the rosettes will be found to persist for 

 a long time, and tend to bind the individuals of the 

 colony together as a whole. 



Compactness of growth, which is here well 



