220 RHIZOMES AND ROOTS. 



(105) Bryony Root. 



The root of Bryonia dioica, Linn. (N.O. Cucurbitacese). 

 The root presents the following structure : 



(1) Cork, composed of several layers of cells with yellow walls ; 

 in surface view these cells are either axially elongated or poly- 

 gonal and isodiametric. 



(2) Cortex, which is very narrow, consisting of parenchymatous 

 cells containing starch and sclerenchymatous cells with slightly 

 thickened walls. The starch is chiefly in simple oval or 

 rounded grains with a very distinct hilum, but occasional com- 

 pound grains, with two or three component granules, may be 

 found. The cortex also contains small straight or branched 

 laticiferous vessels. 



(3) Bast Ring, in which laticiferous vessels are also found, 

 together with sieve tubes, the latter being distinguished by their 

 larger size. 



(4) Wood, consisting principally of parenchyma, in which there 

 are numerous radially arranged groups of vessels. These groups 

 consist of large pitted and reticulated vessels surrounded by 

 tracheids. 



The diagnostic characters of powdered bryony root are 



(a) The starch grains. 



(b) The large vessels. 



(c) The large-celled cork. 



(d) The absence of bast fibres and crystals. 



