42 PRACTICAL COURSE IN BOTANY 
various points near the base of the hypocotyl and spread out 
in every direction, thus giving rise to the fibrous roots of 
grains and grasses. 
38. Root hairs. — Notice the grains of sand or sawdust 
that cling to the rootlets of plants grown in a bedding of that 
kind. Examine with a lens and see if you 
can account for their presence. Lay the root 
in water on a bit of glass, hold up to the light 
and look for root hairs ; on what part are they 
most abundant? 
The hairs are the chief agents in absorbing 
moisture from the soil. They do not last 
very long, but are constantly dying and being 
renewed in the younger and tenderer parts of 
Fic. 56. —Seed- the root. These are usually broken away in 
ling of wheat, with tearing the roots from the soil, so that it is not 
id easy to detect the hairs except in seedlings, 
even with a microscope. In oat, maple, and radish seedlings 
they are very abundant and clearly visible to the naked eye. 
The amount of absorbing surface on a 
root is greatly increased by their presence. 
39. The root cap.— Look at the tip of 
the root through your lens and notice the b 
soft, transparent crescent or horseshoe- 
shaped mass in which it terminates. This 
is the root cap and serves to protect the 
tender parts behind it as the roots burrow 
their way through the soil. Being soft c 
and yielding, it is not so likely to be in- Egy Oil > Latent 
: : ; matic section of a root 
jured by the hard substances with which _ tip: a, cortex; 6, central 
it comes in contact as would be the more nts — ae 
compact tissue of the roots. It is composed _ situated; ¢, root cap ; g, 
of loose cells out of which the solid root 7°” ™=?°™™ 
substance is being formed; the growing point of the root, 
g, is at the extremity of the tip just behind the cap, c (Fig. 57). 
The cap is very apparent in a seedling of corn, and can easily 
