72 LEAVES. 



(40) Jaborandi Leaves. 



The leaves of Pilocarpus Jaborandi, Holmes (N.O. Kutacese). 



The cells of the upper epidermis are polygonal with straight or 

 slightly undulating walls and are covered with a very thick and 

 strongly striated cuticle. 



The cells of the lower epidermis are similar, but at most only 

 slightly striated. The stomata, which occur on the under surface 

 only, are surrounded by four or five tangentially arranged cells. 

 Hairs are also occasionally to be found on the under surface ; 

 they are unicellular, conical, and have thick, smooth walls. 



Here and there a group of epidermal cells may be found that are 

 distinguished by their smaller size and thinner walls ; these mark 

 the insertion of external glands, the walls of which, however, are 

 thin and not conspicuous. 



The mesophyll is heterogeneous and asymmetrical ; the spongy 

 parenchyma is composed of irregular cells, many of which con- 

 tain cluster crystals of calcium oxalate. In this tissue there are 

 numerous internal oil-glands. 



The midrib is nearly flat on the upper surface, but strongly 

 arched below. There are two bundles of wood ; the upper and 

 smaller is nearly straight, whilst the lower and larger is nearly 

 semicircular. Outside the wood is the bast, containing cluster 

 crystals of calcium oxalate, and beyond the bast an interrupted 

 circle of lignified pericyclic fibres. 



The diagnostic characters of powdered Jaborandi leaves are : 



(a) The characteristic stomata . 



(b) The upper epidermis strongly striated. 



(c) The lignified pericylic fibres. 



(d) The oil-glands, which, however, are seldom found intact in the 

 powder. 



(e) The length of the palisade cells (30 to 45/i). 



