102 ROCK PLANTS OF THE PASTURES 



runners appear to be shooting straight up into the 

 air. As a matter of fact, this is merely due to 

 the circumstance that the rosettes are tilted through 

 a high angle and the runners are always produced 

 at right angles to the rosettes. Other runners are 

 growing over the sides of the lichen-covered rocks, 

 and on the right-hand side of the picture two runners 

 are seen going round the corner, as it were, to another 

 crevice to seek "fresh Woods, and Pastures new." 



In the photograph on Plate XXIII., a colony is 

 seen boldly letting itself down over the face of the 

 rocks from ledge to ledge. The runners seen on the 

 left-hand side are obviously creeping or marching 

 down hill. On the right, the plant, by means of its 

 enormously elongated runners, has, as it were, made 

 a ladder of itself and is descending over the miniature 

 precipice. The relation of the runner to the rosette 

 can be clearly seen in this photograph. 



In the two Alpine species described here, the 

 runners are wonderfully persistent. Kerner has, 

 however, described another species (S. globiferum, 

 Linn. = S. soboliferum, Sims), which does not occur 

 in Switzerland, in which the young rosettes soon 

 become detached from the thread-like runners, and 

 are blown by the wind from one rocky ledge to 

 another, and eventually find refuge in some crevice, 

 where a new colony is founded. This vegetative 

 means of distribution has not, however, been observed 

 in the case of either the Spider's-web or the Mountain 

 House-leek. 



