78,79.] FORMS OF SCALE-BEARING STEMS. 93 



ing horizontally in all directions beneath the soil, 

 annually sending up from its terminal buds erect stems 

 into the air. The Witch-grass is an example. Such 

 plants are a sore evil to the garden. They can have 

 no better cultivation than to be torn and cut to pieces 

 by the spade of the angry gardener, since they are 

 thus multiplied as many times as there are fragments. 



232. Repent stems of this kind are not, however, without their use. They 

 frequently abound in loose, sandy soil, which they serve to bind and secure 

 against the inroads of the water and even the sea itself. Holland is said to 

 owe its very existence to the repent stems of such plants as the Mat-grass 

 (Arundo arenaria), Carex arenaria, and Elymus arenarius, which overrun the 

 artificial dykes upon its shores, and by their innumerable roots and creepers 

 apparently bind the loose sand into a firm barrier against the washing of the 

 waves. So the turf, chiefly composed of repent Grass-stems, forms the only 

 security of our own sandy or clayey hills against the washing rains. 



258, Rhizoma of Solomon's Seal (Polygonatum multiflorum). a, Fragment of the first year's growth ; 

 b, the second year's growth ; c, growth of the third year ; d, growth of the present (fourth) year, bearing 

 the stem, which, on decaying, will leave a scar (seal) like the rest. 259, Premorse root of Trillium erectum. 



233. THE RHIZOME, or ROOT-STOCK, differs from the 

 creeper only in being shorter and thicker, having its 

 internodes but partially developed. It is a prostrate, 

 fleshy, rooting stem, either wholly or partially subter- 

 ranean, often scaly with the bases of undeveloped 

 leaves, or marked with the scars of former leaves, and 

 yearly producing new shoots and roots. Such is the 

 fleshy, horizontal portion of the Blood-root, Sweet-flag, 

 Water-lily, and Bramble (the latter hardly different 

 from the creeper). 



