104 THE STEM. 



tween shrubs and trees there is every intermediate gradation. A 

 shrub which approaches a tree in size, or imitates it in port, is said 

 to be arborescent. 



162. Trees are woody plants with single trunks, which attain at 

 least five times the human stature. 



163. A Culm is a name applied to the peculiar jointed stem of 

 Grasses and Sedges, whether herbaceous, as in most Grasses, or 

 woody or arborescent, as in the Bamboo. 



164. A Caildex is a name usually applied to a Palm-stem (Fig. 

 166), to that of a Tree Fern (Fig. 94), and to any persistent, 

 erect, or ascending, root-like forms of main stems. It is some- 

 times nearly synonymous with the rhizoma (174). 



165. Those stems which are too weak to stand upright, but re- 

 cline on the ground, rising, however, towards the extremity, are 

 said to be decumbent : if they rise obliquely from near the base, 

 they are said to be ascending. When they trail flat on the ground, 

 they are procumbent, prostrate, or running ; and when such stems 

 strike root from their lower surface, as they are apt to do, they are 

 said to be creeping, or repent. 



166. They are called Climbers, when they cling to neighbouring 

 objects for support ; whether by tendrils, as the Vine and Passion- 

 flower; by their leaf-stalks, as the Virgin's Bower (Clematis), or 

 by aerial rootlets, as the Poison Oak (Rhus) ; and Twiners, or 

 twining plants, when they rise, like the Convolvulus, by coiling 

 spirally around stems or other bodies within their reach. Other 

 mo'difications of the stem or branches have received particular 

 names, some of which merit notice from having undoubtedly sug- 

 gested several important operations in horticulture. 



167. A Stolon is a form of branch which curves or falls down to 

 the ground, where, favored by shade and moisture, it strikes root, 

 and then forms an ascending stem, which is thus capable of draw- 

 ing its nourishment directly from the soil. The portion which 

 connects it with the parent stem at length perishing, the new indi- 

 vidual acquires an entirely separate existence. The Currant, 

 Gooseberry, &c., multiply in this way, and doubtless suggested to 

 the gardener the operation of layering ; in which he not only takes 

 advantage of and accelerates the attempts of nature, but incites 

 their production in species which do not ordinarily multiply in this 

 manner. Plants which spread or multiply by this natural layering 

 are said to be stolon if erous. 



