112 



BOTANY 



FART 1 



HADROME, and the sieve-tube portion the PHLOEM or LEPTOME ( no ). 

 The distinction of the two components of the vascular bundle is 

 most evident from transverse sections (Figs. 121, 123), with which 

 the longitudinal section (Fig. 122) should be compared. The 

 vascular portion contains TRACHE/E and TRACHEIDES as most essential 

 for the fulfilment of its function of water conduction (a, sp, m, Figs. 



Fio. 123. Transverse section of a vascular bundle from a stolon of Ranunculus repens. s, Spiral 

 tracheides ; m, vessel with bordered pits ; c, cambium ; v, sieve-tubes ; vg, sheath, (x 180.) 



121, 122), or tracheides alone, and, in addition, living, elongated 

 parenchymatous cells that may be designated XYLEM or WOOD 

 PARENCHYMA. In the phloem portion the most essential elements 

 are the SIEVE-TUBES (#), which serve for the conveyance of albuminous 

 matter. They are always accompanied by other living cells ; either 

 by the so-called COMPANION CELLS (s), or in addition by elongated 

 parenchymatous cells, or by the parenchyma alone. Companion 

 cells only occur in the phloem of Angiosperms. They are sister 



