ITS SUBTERRANEAN MODIFICATIONS. 



107 



grow, also, in the opposite direction from roots. So, likewise, what 

 were called (as they are still popularly considered) creeping roots 

 are really subterranean branches ; such as those of the Mint, and 

 of most Sedges and Grasses. Some of these, such as the Carex 

 arerlaria (Fig. 137) of Europe, render important service in binding 

 the shifting sands of the sea-shore. Others, like the Couch-Grass, 

 are often very troublesome to the agriculturist, who finds it next to 

 impossible to destroy them by the ordinary operations of husbandry ; 

 for, being furnished with buds and roots at every node, which are 

 extremely tenacious of life, when torn in pieces by the plough, 

 each fragment is only placed in the more favorable condition for 

 becoming an independent plant. The Nut-Grass (Cyperus Hydra), 

 an equally troublesome pest to the planters of Carolina and Geor- 

 gia, is similarly constituted ; and besides, the interminable subter- 

 ranean branches bear tubers, or reservoirs of nutritive matter, in 

 their course, which have still greater powers of vitality, as they 

 contain a copious store of food for the development of the .buds 

 they bear. The name of 



174. Rhizoma OF Rootslock is applied in a general way to all 

 these perennial, horizontally elongated, and more or less subterra- 

 nean root-like forms of the stem ; and more particularly to those 

 which are thickened by the accumulation of nutritive matter in 



FIG. 137. Creeping subterranean stem of Carex arenaria. 



FIG. 133. Rhizoma of Diphylleia cymosa, showing six years' growth, and a bud for the 

 seventh : a, the bud : b, base of the stalk of the current year: c, scar left by the decay of the 

 annual stalk of the year before; and beyond are the scars of previous years. 



