174 



STEMS 



the shade of surrounding plants and, therefore, thrive best where 

 erect plants are few, as on sandy beaches or river banks. 



However, prostrate stems have some distinct advantages over 

 erect ones. Since they do not have to support much weight, they 



FIG. 149. One of the giant trees of the West, called 

 " Grizzly Giant." From Forestry Bulletin. 



can grow very long and slender without developing much strength- 

 ening tissue. Furthermore, they are not so much exposed to loss 

 of water by evaporation as erect stems are. The prostrate posi- 

 tion is also more favorable for vegetative propagation, for as the 



