SPECIAL FORMS. 



57 



scales , and the advancing apex rises at length into an ordinary 

 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 activity ; and 

 the cutting or tearing of the rootstock into 

 pieces b} T 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 (Cyperus 

 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- 

 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 } r ear 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. 98. Slender rhizoma of Carex arenaria, of Europe, which binds shifting sands 

 of the sea-shore. 



FIG. 99. Eootstocks, 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. 



