28 THE ROOT. 



30. Stkucture of the Root. — ^The Root {radix) is tlie basis 

 of the plant, or that part which usually enters the- earth, and 

 extends in a direction contrary to the growth of the stem ; it 

 originates with the rctdicle of the seed, supports the plant in an 

 upright position, and at the same time gives nourishment to 

 every part of it. There are exceptions to the general fact of a 

 root being fixed in the ground ; some plants, as the pond-lily, 

 growfc in water, and are called aquatic, some, like the mistletoe, 

 nave no root, but fix themselves upon other plants, and derive 

 sustenance from them ; such are called lyarasites."^ 



The root consists of the caudex^ the main body of the root ; 

 fihrils^ the finer branches, which are the true roots ; and the 

 spongioles^ extremities of the root, which are composed of cel- 

 lular tissue, and ducts or mouths, w^hich absorb nutritious 

 "juices. The nourishment ascending through the stem expe- 

 riences in the leaves and green j^arts of the plant an important 

 change, effected, in part, through the agency of air and light ; 

 and a portion of it, through a different set of vessels, flows 

 back, in what is called the returning sap, or cambium. The 

 nourishment thus digested is returned to the stem and root, 

 and is expended in the formation of new rootlets and branches. 

 The downward direction of the root is accounted for by the 

 delicacy of the fibers, which causes them to shun the light and 

 air, and also by the effects of gravitation, which they have not 

 the force to resist. The summit of the root, or that part which 

 connects it with the ascending axis, is called the collura^ or 

 neck ; any injury to this part is followed by the death of the 

 plant. 



31. Duration of Roots. — Roots, with respect to duration^ 

 are anmial^ biennial^ or j9<?r^w7im^. 



An7iual Roots live but one year. They come from the seed 

 in the spring, and die in autumn, including such as are raised 

 from the seed every year ; as peas, beans, cucumbers, &c. The 

 flowering process and the maturing of the fruit exhaust the 

 plant, and having no nourishment accumulated in its dry 

 ' nbrous root, it j^erishes as soon as its seed is perfected. Bien- 

 nial Roots live two years. They do not produce any flowers 

 the first season ; the next summer they blossom, the seeds 

 mature, and the roots die. The roots of cabbages are often, 

 after the first season, preserved during the winter. In the 

 spring they are set out in gardens, and j^roduce flowers ; the 

 ovary grows into a pod which contains the seed. The root 



* The word parasite, from tlie Greek para, with, and sitos, corn, was first applied to those who had 

 the care of the corn used in religious ceremonies, and were allowed a sliare of the sacrifice ; afterward it 

 was applied to those who depended on the great, and earned their welcome by flattery. 



30. The root— Parts of the root —;U. Annual roots— Biennial. 



