THE KOOT. 



81 



wholly subterranean. This root, by the fibers spreading and 

 interlacing; themselves, renders a soil more permanent. Hol- 

 land would be liable to be washed away by the action ■ i* water, 

 were not its coasts bound together by these creeping i^lants, 

 which will grow in sandy, light soils, that scarcely produce any 

 other vegetation. 



. TheGramdatedroot {Yig. 17) con- Fig. ii 



sists of little bulbs or ttihei^s, strung 

 together by a thread-like radicle, 

 as in the common wood-sorrel. 

 By some, this is called moiiili- 

 forrn^ from moniU^ a beaded 



necklace. The potato and other Uobers are by late botanists 

 classed as sMerranean sterns^ capable of developing leaf-buds ; 

 these may consist of one tiihtr ; as in the potato (Fig. 18, d) ; or 

 of many^ connected by fila- 

 ments, as in the artichoke 

 (b). These tubers are reser- 



Fig. 19. 



voirs of moistm'e, nourish- 

 ment, and vital energy. . The 

 potato is an excrescence, 

 proceeding from the real 

 root. It is a singular fact that this nutritious substance is the 

 ]>roduct of a plant whose fruit is poisonous. The eye in the 

 ] otato is a hud. The root of some of the orchis plants (Fig. 

 18, c) consists of two ovate tubers ; these roots are said to be 

 tuberiferous. 



b. Yig. 19, at a, shows a root of the Spiranthes, 

 one of the orchis tribe of pUmts. It bears a mass 

 of crowded, club-shaped tubers : this is called a 

 grumose root. At 6 is a fanciulated tuberous 

 root, as in the dahlia, peonia, and asphodel. At 

 c, the tubers are suspended from the caudex, as 

 in the root of the Spiroea JUipendida. 



36. Bulbs. — ^These are subterranean 

 leaf-buds covered with scales arising 

 from a shortened axis. From the cen- 

 ter of the bulb a shoot or herbaceous 

 stem is produced, which dies down. 

 New bulbs (called turions) are produced from the subterranean 

 axis, formed like buds in the center of a scale. The new 

 bulb sometimes remains attached to the parent bulb, and sends 

 up an axis and leaves, sometimes forms an independent plant. 

 The new bulb feeds on the parent one until it is wholly ab- 

 sorbed. 



Granulated root— Tubers not the real root.— .36. Bulba. 



