STEMS 44 
multiplication of plants in others. In many plants, as the 
prostrate stem advances over the ground, roots develop from 
the nodes and enter the soil, leaves are formed, and a new 
plant is started, which may become independent by the 
death of the older parts. In this way a plant may spread 
over the ground, multiplying itself indefinitely. So 
effective is this method of multiplication that plants with 
erect stems often make use of it, sending out from near the 
base special prostrate branches which advance over the 
ground and start new plants. A very i 
familiar illustration is furnished by the 
strawberry-plant, which sends out peculiar 
leafless runners to strike root at the tip and 
start new plants, which become independent 
by the death of the runners (Fig. 46). 
These various prostrate stems illustrate 
the fact that nodes can produce not only 
leaves and branches, but also roots, if 
placed in suitable conditions. Advantage 
is taken of this fact in the common process 
of layering, in which such stems as those 
of blackberries and raspberries are bent 
down to the ground and covered with soil, 
when the nodes strike root and new plants 
are started. 
(3) Climbing stems.—A great many 
plants have developed the ability to sus- 
tain themselves by using supports. Al- 
though not able to stand alone, by using 
these supports they may attain great length 4,, “G7 bean 
and display their leaves to light even in a _ twining about a 
dense forest. This climbing is effected in nape 
a variety of ways. In some cases, as the morning-glory, 
bean, and hop-vine, the stem twines about the support, 
such plants often being distinguished as twiners (Fig. 47); 
t 
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