33] 



CHAPTER II. THE TISSUES. 



131 



other to form a closed system ; this is characteristically the case 

 where the venation is parallel (e.g. Monocotyledons, see p. 38). 

 In others, again, the finer branches anastomose, forming a network 

 from the meshes of which the ultimate branches project among the 

 mesophyll-cells as free ends : this obtains generally among Dicoty- 



FIG. 105. A Tranverse section of an open conjoint, collateral, vascular bundle in the 

 stem of the Sunflower, if Pith. X Xylem. C Cambium. P Phloem and pericycle. 

 R Cortex ; s small, and s' large spiral vessels (protoxylem) ; t pitted vessels ; t' pitted 

 vessels in course of formation from the cambium ; h wood-fibres ; sb sieve tubes ; b fibres 

 of the heterogeneous pericycle; e endodermis or bundle-sheath; tc inter-fascicular con- 

 junctive tissue. B Radial vertical section through a similar bundle (somewhat simplified) 

 lettered like the former. ( x 150.) 



ledons. The free ends of the bundles consist of one or two rows 

 of short tracheids with close spiral markings ; no sieve-tubes can 



