86 LEAVES. 



(47) Stramonium Leaves. 



The leaves of Datura Stramonium, Linn. (N.O. Solanacese). 



The epidermis of the upper surface of the leaf closely resembles 

 that of the lower surface. Both are composed of cells with 

 undulating or sinuous walls and bear stomata and simple as well as 

 glandular hairs. 



The stomata are surrounded by three (or sometimes four) cells, 

 one of which is smaller than the others, an arrangement that is 

 common in solanaceous leaves. 



The simple hairs are uniserial, and conical; they are composed 

 of from three to five cells, the walls of which are warty and not 

 very thick. 



The glandular hairs are short ; the gland is oval, pluricellular, 

 and borne upon a little pedicel. 



The mesophyll is heterogeneous and asymmetrical. Both the 

 palisade tissue and the spongy parenchyma contain simple pris- 

 matic crystals as well as cluster crystals of calcium oxalate. 



The midrib is convex above and very convex below; the wood 

 is strongly curved and there is a layer of bast above as well as 

 below it. Neither bast nor peri cycle contain any lignified elements. 

 In addition to prismatic and cluster crystals of calcium oxalate 

 the cortical tissue of the midrib contains cells filled with sandy 

 crystals ; these cells are large and often superposed. 



The diagnostic characters of powdered stramonium leaves are : 



(a) The characteristic hairs. 



(b) 



(c) The stomata of solanaceous type. 



(d) The absence of pericyclic fibres. 



