Minnesota Plant Life. 



419 



sist of the vegetation around it, but the stem may lie flat upon 

 the ground, as does the strawberry runner. Thus supported, it 

 can remain slim and fragile, but it could not do this if it main- 



FIG. 211. Bur oak and bracken fern. Illustrates relation between strength of stem and the 

 weight to be borne. After photograph by Hibbard. 



tained an erect habit. Again, water surrounding the stem and 

 leaves of a plant may furnish the necessary support, and the 

 plant is free to produce slender organs which collapse when 



