86 



THE ROOT. 



downwards, as in the Radish, Fig. 113; or napiform or turnip- 

 shaped^ when much swollen at the base, so as to become broader 

 than long. If some of the branches or fibres are thickened, instead 

 of the main axis, the root is said to be fasciculated or clustered, 

 as in Fig. 114 ; or tuberiferous or tuberous, when they assume the 

 form of rounded knobs, as in Fig. 115; or palmate, when the 

 knobs are branched, as in Fig. 116. These must not be con- 

 founded with tubers, such as potatoes, which are forms of stems. 

 Most of these are biennial. Such plants (of which the Radish, 

 Carrot, Beet, and Turnip, among our esculents, are familiar exam- 

 ples) neither flower the first season, nor even expend in the pro- 

 duction of stems and branches much of the nourishment they gen- 

 erate ; but, forming a large tuft of leaves at the very surface of 

 the ground, they accumulate in the root nearly the whole sum- 

 mer's supply of nourishment. When vegetation is resumed the 

 following spring, they make a strong and rapid growth, shooting 

 forth a large stem, and bearing flowers, fruit, and seed, almost 

 wholly at the expense of the accumulation of the previous year ; 

 this store is soon consumed, therefore; and the plant, meanwhile 

 neglecting to form new roots, perishes from exhaustion. 



129. Perennial Roots, A third class of herbs, and all woody 

 plants, do not so absolutely depend upon the stock of the previous 

 season, but annually produce new roots and form new accumula- 

 tions ; sometimes in separate portions of the root, as in the Dahlia 



FIG. 111-116. Different kinds of roots. 



