264 RHIZOMES AND ROOTS. 



(127) Turmeric Rhizome. 



The rhizome of Curcuma longa, Linn. (N.O. Scitamineae). 

 The rhizome presents the following structure: 



(1) Epidermis, of flattened cells, which are polygonal in sur- 

 tace view, and exhibit not very conspicuous pits on their side 

 walls. It bears stomata and rounded scars of fallen hairs. 



(2) Hypodevma, consisting of several layers of tangentially 

 elongated polygonal cells, amongst which scattered oleoresin 

 cells may be seen. Occasionally this tissue is absent. 



(3) Cork, consisting of three or four rows of cork cells. 



(4) Phelloderm, of the usual character. 



(5) Cortex, of considerable extent, composed of polygonal 

 parenchymatous cells, filled with starch and permeated with 

 yellow colouring matter. The latter is changed to a deep 

 crimson red with concentrated sulphuric acid; if alcohol is 

 present the crimson substance dissolves in it. Much of the 

 starch has been transformed by heat into gelatinised masses, 

 but some intact grains may usually be found ; they resemble 

 ginger starch in outline, but are more strongly flattened (com- 

 pare Fig. 9, p. 15) The cortex also contains numerous oleoresin 

 cells, the secretion in which may be granular, or form droplets or 

 irregular masses. It is traversed by vascular bundles (leaf 

 traces), consisting of vessels and bast, but destitute of any 

 sheath of fibres. 



Starch grains that have escaped gelatinisation may also be 

 found; they resemble those of Fig. 9 (p. 15). 



^6) Endodermis, of rectangular suberised cells. 



(7) Stele, composed of parenchymatous tissue, similar to that 

 of the cortex and traversed by similar vascular bundles. 



The diagnostic characters of powdered turmeric rhizome 

 are: 



(a) The yellow masses of gelatinised starch. 



(b) The presence of an epidermis 



(c) The characteristic vessels. 



(d) The presence of oleoresin cells. 



(e) The sulphuric acid reaction. 



