54 LEAVE 



(31) Belladonna Leaves. 



The leaves of Atropa Belladonna, Linn. (N.O. Solanacete). 



The epidermis is composed of very large cells (up to 120//, 

 long) with sinuous walls, and is covered with a striated cuticle. 



Stomata occur on both sides, and so also do simple and 

 glandular hairs, but many leaves are nearly glabrous. 



The stomata are surrounded by three or four cells, one of 

 which is smaller than the others ; this peculiarity has been 

 observed in most solanaceous leaves. 



The simple hairs are conical and uniserial, consisting usually 

 of three or four cells. 



The glandular hairs vary considerably in appearance. Some 

 are small, and consist of a unicellular or pluricellular gland 

 supported upon a short pedicel ; others are longer and composed of 

 several superposed cells terminated by a rounded unicellular gland, 

 or by a large pluricellular one with horizontal and vertical 

 walls. 



The mesophyll is heterogeneous and asymmetrical. Amongst 

 the cells of the spongy parenchyma, which vary in shape, are 

 some that are usually larger, and filled with sandy crystals of 

 calcium oxalate. 



The midrib is bi-con vex ; the wood is only slightly arched, and 

 bounded by bast on both upper and under surfaces (bi-collateral 

 bundles) as in all solanaceous leaves. Neither bast nor pericycle 

 contains fibres. In the cortical tissue there are cells filled with 

 sandy crystals of caicium oxalate. 



The diagnostic characters of powdered belladonna leaves are : 



(a) The large epidermal cells with wavy ivalls and striated 

 cuticle. 



(b) The stomita surrounded by three or four cells, one of which is 

 smaller than the others. 



(c^ The cells filled with sandy crystals, 

 (d) The absence of pericyclic fibres. 



