66, 67.] 



THE ROOT. 



79 



office is twofold ; viz., to support the plant in its posi- 

 tion, and to imbibe from the soil the food necessary to 

 the growth of the plant. 



198. The leading propensity of the root is to divide 

 itself; and its only normal appendages are branches, 

 branchlets, fibers, and fibrillse, which are multiplied to 

 an indefinite extent, corresponding with the multipli- 

 cation of the leaves, twigs, etc., 



above. This at once insures a firm 

 hold upon the earth, and brings a 

 large absorbing surface in contact 

 with the moist soil. 



199. The summit of the root, 

 or that place where the root meets 

 the stem, is called the collum ; the 

 remote, opposite extremities of the 

 fine rootlets, or fibers, are covered 

 by dry, protective cells, forming a 

 root-cap ; the sides of these fibers 

 are chiefly active in absorbing 

 liquid nourishment, and are mostly 

 covered by root-hairs, which in- 

 crease their absorbing surface. The hairs arise from 

 the tender epidermis or skin, and perish when that 

 thickens into bark. They are developed and perish 

 annually with the leaves, whose servants they are. 

 Few of them remain after the fall of the leaf. This 

 fact plainly indicates that the proper time for trans- 

 planting trees or shrubs is the late Autumn, Winter, 

 or early Spring, when there are but few tender fibrillae 

 to be injured. 



200. Two modes of root-development are definitely 

 distinguished. First, the AXIAL MODE is that where 



236, Extremity of a rootlet of Ma- 

 e, with its hairs and root -cap (a) 



