234 RHIZOMES AND ROOTS. 



(112) White Hellebore. 



The rhizome and roots of Veratrum album. Linn. (N.O. 

 Liliacese). 



The rhizome presents the following structure : 



(1) Tegumentary Tissue, consisting of several layers of dark 

 browa, slightly thickened, suberised, parenchymatous cells 

 which in surface view are irregular, polygonal and provided 

 with wavy walls. 



(2) Collenchyma. Subjacent to the tegumentary tissue is a 

 layer of collenchymatous cells exhibiting the usual characters. 



(3) Cortical Parenchyma, composed of rounded-polygonal cells 

 with intercellular spaces. Most of these cells contain starch 

 in small, simple and compound grains ; the former are rounded, 

 the latter consist of three or four angular component grains. 

 Some of the cells are filled with a large bundle of acicular crystals 

 of calcium oxalate. This tissue is also traversed by a number of 

 fibrovascular bundles (leaf traces). 



(4) Endodermis, the cells of which are yellowish brown in 

 colour and thickened on their inner and lateral walls. 



(5) Stele, consisting of parenchymatous tissue resembling that 

 of the cortex and traversed by fibrovascular bundles. The 

 latter contain principally pitted vessels and are supported by a 

 sheath of lignified thickened fibres. 



The structure of the root is different. The cells of the 

 epidermis have thickened brown walls and are strongly axially 

 elongated. The cells of the cortical parenchyma are also 

 axially elongated ; they contain starch grains and acicular 

 calcium oxalate crystals. The cells of the endodermis are 

 likewise strongly elongated ; their walls are thickened, pitted, and 

 of a brownish colour. The stele contains wood bundles 

 alternating with bast bundles and supported by sclerenchy- 

 matous fibres which extend to the centre of the root. 



The diagnostic characters of white hellebore are : 



(a) The starch grains. 



(b) The cells of the endodermis. 



(c) The abundant raphides. 



(d) The red colour gradually produced by the action of 



sulphuric acid. 



