84 



PRACTICAL COURSE IN BOTANY 



have been compelled to take on the annual habit as an 

 adaptation to climate. 



95. Direction and habit of growth. As to manner of 

 growth, there are many forms, from the upright boles of 



FIG. 94. Orange hawk- 

 weed with runners. 



FIG. 95. Prostrate stem of Lycopodium 

 with assurgent branches. 



the beech and pine to the trailing, prostrate, and creeping 

 stems of which we have examples in the 

 running periwinkle, the prostrate spurge 

 and the creeping partridge berry (Mitchella 

 repens), respectively. Trailing and pros- 

 trate stems are very apt to become 

 creepers by the development of adventi- 

 tious roots at their nodes wherever they 

 come in contact with the soil. The root- 

 ing stems of dewberries, the runners and 

 stolons of strawberries and currants, are 

 familiar examples. 



Between the extremes of prostrate and 

 upright, stems may be inclined or bent in 



FIG. 90. Diagram 

 of stem growth : ps, 



surface of the ground ; various degrees. As shown in Fig. 96, 



e, erect position; d, ,-, -i f i- , 



declined ; a, assurgent ; there are two modes of inclination : assur- 

 gent, a, from the prostrate, p, toward the 



p, prostrate ; u, ver- 

 tical direction under- 



ground. 



upright, e; and declined, d, from the upright 



