LECT. VII.] ANATOMY OF STEMS. 299 



It is necessary to notice, particularly, the 

 structure of one variety of the solid, herbaceous, 

 monocotyledonous stems ; as it constitutes the 

 link betwixt the solid and the fistular monoco- 

 tyledons. It is articulated, giving off leaves at 

 the joints only ; and these are sheathing or em- 

 brace the stem. On dissection, we find the vas- 

 cular bundles, which can scarcely be called lig- 

 neous, enclosed in a cellular parenchyma, and 

 running in straight lines between the joints ; but 

 at these they inosculate in arches, and send off 

 horizontal branches, some of which terminate in 

 the leaves and others in the lateral shoots that 

 originate at their basis. This structure is beau- 

 tifully displayed in the stem of Spiderwort, Trade- 

 scantia Virginica, in which the circles forming 

 the annular vessels being nearly opaque, the 

 course of the vascular bundles is readily traced ; 

 and the manner in which the vessels are given off, 

 and inosculate, distinctly seen by the aid of the 

 microscope *. 



in the leaves, if these be large or mostly immersed, as for in- 

 stance the Common Reed-mace. 



* Vide fig. 9 and 10, Plate 5. Fig. 9, a. a. a. a. a. a. the 

 vascular cords, as seen by means of a good lens by reflected 

 light, forming arches at the joint ; b. 6. the base of the leaf, 

 with the vessels which supply it proceeding nearly from the 

 centre of the joint ; d. the fragment of a lateral shoot, the 

 vascular bundles connected with which are seen originating 

 from the same spot as those of the leaf. Fig. 10, a Small por- 

 tion of the joint highly magnified, to display the structure of 



