•y^ THE STEM. 



' 181. The raiizoMA, or rootstock, is a prostrate, Ihickeiied, 

 rooting stem, either wholly or partially subterranean, often cov- 

 ered ^th scales, which are the rudiments of leaves, or marked 

 ^vith scars, which indicate the insertion of former leaves, and 

 yearly producing both shoots and roots. Such is the thickened, 

 horizontal portion of the blood-root (Sanguinaria), sweet flag 

 ( Calamus ) , and the bramble ( Rubus ) .j 



18" The CKEEPER differs from the ahove only /m size, consisting of slender 

 branches, exceedingly tenacious of life, cxtendhig horizontally in all directions, 

 and to consideraWe distances beneath the surface, sending out roots and branches 

 at intervals. The witch-grass (Triticum rcpens) is an example.. Such plants 

 are a sore evil to the garden. They can have no better cultivation than to be 

 torn and cut in pieces by the spade of the angry gai'dener, since they are thus 

 multiplied as many times as there are fragments. 



a Repent stems of this kind are not, however, ^^4tll0ut their use. (They Ire- 

 quently abound in loose, sandy soil, which they scnc to bind down and secure 

 ao-ainst the inroads of water, and even of the sea itself. Holland is said to owe its 

 very existence to certain repent stems, by wliich its sliores are apparently bound 

 to-ether. ISIuch of the surface of that country is well knoNvn to be even below 

 the level of the sea. To protect it from inundation, dikes of earth have been 

 built, with immense labor, along tlie coast. These dikes are overspread with a 

 tluck growth of such plants as the mat-grass, or Arundo arenana, the Carex are- 

 naria, and the Elymus arenarius, by the innumerable roots and creepers of which 

 they are enabled to resist the wasliing of the waves 



183. To AERIAL STEMS belong the following varieties; — caulis, 

 nmner, scape, vine, trunk, sucker, offset, and stolon. 



184 Caulis (stem) is the term commonly applied to the aerial 

 stems of herbaceous plants, which are annual in duration, and 

 destitute of woody tissue. Caulescent and acaulescent are con 

 venient terms, denoting, the former the presence, and the latter 

 the absence of the cauhs, or aerial stem. 



185 RuNNEK. . This is a prostrate, filiform stem, or shoot, ex- 

 tending itself along the surface of the ground, and throwing out 

 roots and leaves at its extremity, which become- a new plant, 

 soon putting forth new runners in its turn. Ex straAvbeny. 



186. The scape is a stem which springs from the summit of 

 the root, or rootstock, and bears the inflorescence of the plant, 

 but not its fohage. Ex. Sarracenia, daffodil, several species of 

 the Orchis, &c. The foliage of such plants is usually radnal, 

 that is, springing from the root or subterranean stem. 



