CHAPTER VII 
THE ROOT 
The Root is that part of the plant that grows into or toward 
the soil, that never develops leaves, rather rarely produces buds, 
and whose growing apex is covered by a cap. 
The chief functions of a root are absorption, storage and 
support. Its principal function is the absorption of nutriment 
and to this end it generally has branches called Rooters that 
are covered with Root-nairs which largely increase the absorb- 
Fic. 89.—Cross-section of rootlet in the region of the root-hairs. (From Stevens.) 
ing surface. These Roor-Harrs are of minute and simple 
structure, being merely elongations of the epidermis of the root, 
for a short distance back of the root cap, into slender tubes with 
thin walls. Like other living cells, each shows cytoplasm, sap 
vacuoles containing cell sap, a nucleus with nuclear membrane, 
outer plasma membrane against the covering cell wall of 
cellulose and vacuolar membranes around sap vacuoles. That 
portion of the epidermis which bears root-hairs is called the 
PitiFEROus LAYER. 
Som. AND WaTER Retation.—Under conditions favorable 
to the growth of land plants, the soil is open and porous, the 
particles of soil being separated by spaces containing air, while 
every soil particle is enveloped by a film of water. The root- 
hairs are in close contact with these soil particles (F ig. 92) and 
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