70 LEAVES. 



(39) Henna Leaves. 



The leaves of Laivsonia alba, Lam. (N.O. Lythrariese). 



The epidermis of both surfaces is provided with stomata, which 

 are surrounded by four or five cells ; these cells, however, exhibit no 

 regularity in their arrangement. The cuticle is thin on the under 

 surface and, especially above the veins, striated. 



The mesophyll is heterogeneous and symmetrical. There are 

 two rows of palisade cells on either surface, and the lower part of 

 the spongy parenchyma, which is composed of ellipsoidal, rounded 

 or cylindrical cells, is very rich in large cluster-crystals of calcium 

 oxalate. 



The midrib is plano-convex. The wood is curved, and exhibits a 

 layer of bast above as well as below. Between the bast and the 

 lower epidermis there is a well developed arc of pericyclic fibres. 

 The cortical tissue of the midrib is also rich in large cluster-crystals 

 of calcium oxalate. 



The powder often contains the debris of twigs, etc. 



The diagnostic characters of powdered henna leaves are : 



(a) The cuticle, striated over the veins. 



(b) The numerous large cluster-crystals of calcium oxalate. 



(c) The pericyclic fibres. 



