SPECIAL FORMS. 



57 



scales , and the advancing apex rises at length into an ordinarj' 

 stem, while the opposite and older end gradually dies away. A 

 bud forms in the axil of each scale-like leaf, or 

 in some of them ; roots proceed from the nodes 

 in preference ; the destruction of the ascending 

 stem only brings these buds into activitj- ; and 

 the cutting or tearing of the rootstock into 

 pieces by the hoe or plough merely hastens the 

 establishment of as many new plants, each with 

 roots, bud, and a small store of nourishment 

 ready provided. It is this which makes Couch- 

 Grass or Quick-Grass (Triticum repens) very 



troublesome to the agriculturist ; and the Nut-Grass (Cj-perus 

 rotundus, var. Hydra) of the Southern Atlantic States is even 



more so, portions of its rootstock being tuberiferous, i. e. en- 

 larged into a tuber which contains a supply of 

 concentrated nourishment to feed the growth. 



116. Thickened rootstocks are common; 

 nourishing matter, elaborated in the leaves 

 above, being accumulated in them, just as 

 it is in thickened roots, and for the same pur- 990 



pose. (53-55.) Such are the so-called roots of Sweet-Flag, of ^ 

 Ginger, of Iris or Flower-de-Luce (Fig. 216), of Bloodroot, of ' 

 Solomon's Seal (Fig. 100), &c. These grow after the manner 

 of ordinary stems, advancing from year to year by the annual 

 development of a bud at the apex, and emitting roots from the 

 under side or the whole surface. Thus established, the older . 



FIG. 08. Slender rhizoma of Carex arenaria, of Europe, which binds shifting sands 

 of the sea-shore. 



FIG. 99. Rootstocks, or creeping subterranean branches, of the Peppermint. 



FIG. 99". A piece of the rootstock of the Peppermint, enlarged, with its node or joint, 

 and two axillary buds ready to grow. 



