LECT. VI.] THE STEM. ITS DIRECTION. 253 



that the stem extends horizontally, or on the 

 surface of the ground, and sends out roots 

 from below; as in lesser periwinkle, Vinca 

 minor (h), and Ground Ivy, Glechoma hede- 

 racea. Linnaeus, Sir J. E. Smith, and some 

 other authors, describe another variety of the 

 procumbent stem under the term trailing or 

 sarmentose (sarmentosus *) : but the sarment 

 is, properly speaking, not a stem, but merely a 

 runner which performs the same functions as 

 the underground runners, to which pendu- 

 lous tubers are attached. It is, in fact, a vas- 

 cular cord, intended to place the lateral pro- 

 geny of the plant at a convenient distance 

 from the parent, and to convey nourishment 

 to the offset until such time as it takes root 

 and is capable of supporting itself. It is at 

 first sent off from the neck or collet of the 

 root ; but, afterwards, it gives off itself roots 

 at the points where the offsets spring; and, 

 as the manner in which this is effected va- 

 ries, it is of different kinds ; but these shall 

 be demonstrated when we investigate the ap- 

 pendages of the stem. The swimming stem 



* " Sarmentosus, repens, subundus est." Phil Bot. 82. 9. 



" Sarmentosus, trailing. A creeping stem, barren of flowers, 

 " thrown out from the roots for the purpose of increase, is 

 " called sarmentum or flagellum, a runner.'* Smith's Intro* 

 duction, &c. p. 120. 



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