176 A TEXTBOOK: OF GENERAL BOTANY 
so such roots never become very large. Monocotyledonous 
plants are usually anchored in the ground by numerous small 
roots. This is conspicuously the case with large palms such as 
the coconut. 
Aérial roots. Roots are characteristically subterranean struc- 
tures, but they may develop in the air. Such is the case with many 
climbing plants (Fig. 179) 
and also with epiphytes, 
which are plants that grow 
perched on other plants 
(Fig. 2). In both of these 
cases the roots still have 
the functions of absorbing 
water and anchoring the 
plant. In epiphytic plants 
many of the roots grow so 
close to the bark of the 
plant on which they are 
found as to become attached 
to it. They are, at the same 
time, in a fairly favorable 
position for the absorption 
of water. Certain climbing 
plants develop two types 
of roots: small, short roots 
which anchor the plant to 


showing short roots that attach the stem 
to the support, and long ones that grow 
to the ground and absorb water. (x 4) 
its support, and longer ones 
which reach down to the ground and serve more particularly 
for the absorption of water (Fig. 179). 
Incidental functions. Roots have not only the two principal 
functions mentioned above but also functions that are inci- 
dental to these, as well as other functions, such as respiration, 
which are common to all plant parts. We shall find later that 
water absorbed by the roots is taken in very largely by the 
small young roots. In order that this water may reach the 
stem it must pass through the larger roots. In the same way 
