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 
SSB aR, 
Fic. 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 
