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 
Fie. 94. — Orange hawk- 
weed with runners. 
Sa Soe= 
CEES 
EL NY) 
aN f 
Fig. 95.— Prostrate stem of Lycopodium 
with assurgent branches. 
the beech and pine to the trailing, prostrate, and creeping 
w 
Fic. 96.— Diagram 
of stem growth: ps, 
surface of the ground ; 
e, erect position; d, 
declined ; a, assurgent ; 
p, prostrate; wu, ver- 
tical direction under- 
ground, 
stems of which we have examples in the 
running periwinkle, the prostrate spurge 
and the creeping partridge berry (Mvtchella 
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 
various degrees. As shown in Fig. 96, 
there are two modes of inclination: assur- 
gent, a, from the prostrate, p, toward the 
upright, e; and declined, d, from the upright 
