SOIL FORMATION: ROCK DISINTEGRATION. 383 



692. Other plants of rocky regions. — Certain of the higher 

 plants also find means of attachment to the bare rocks of the 

 arctic and mountain regions. The roots penetrate into narrow- 

 crevices in the rock, and are able to draw on the water which is 



Fig. 482. 

 Edge of glacier in Greenland, showing freshly deposited rocks. (From Prof R. S. Tarr.) 



elevated by capillarity. Such plants, however, which live on 

 bare rocks, whether in the arctic or in mountain regions, have 

 leaves which enable them to endure long periods of drought. 

 These plants have either succulent leaves like certain of the stone- 



