root-hairs ; 7c, root-cap ; fc, inner tissues. 
10 ELEMENTARY BOTANY 
accompanying figure, and are, therefore, said to arise endo- 
genously. (Gk. endon = within, and gimoma = to grow.) 
Each branch, like the main root, develops root-hairs behind 
oe 108 Up, and is pro: 
- tected by a root-cap. 
When the primary 
root grows to a 
greater length than 
any of its branches, 
the plant is said to 
have a tap-root ; but 
when, as has already 
been mentioned in 
maize (p. 6), second- 
ary roots, arising 
from other parts of 
the stem, soon equal 
the primary root in 
length, there is no 
tap-root. 
_ A root system, in 
which there is no 
30 main root, is’ de: 
Fic. 13.—MAIN RooT, SHOWING LATERAL  gcribed as fibrous. 
Roors ARISING HENDOGENOUSLY (diagram- oe 
matic). rimary roots may 
_rt, primary root; Jat, lateral roots; rh, be very varied in 

shape, as may be 
seen by comparing the carrot with the turnip ; or they may 
be irregularly swollen, as in the dahlia. 
Functions 4 Toot has two main functions to perform in 
ofa the life of the plant; the primary root, which 
ae erows to considerable length, and is thick and 
stout in the portion nearest the stem, fixes the plant in the 
soil; whilst the extremities of the root and its numerous 
branches are, owing to the root-hairs with which they are 
covered, specially concerned in taking in food and water 
for the plant from the soil. In transplanting, a lump of 
