FOLIA SENNiE. SENNA. 



i8i 



some writers to distinguish the varieties of senna; these 

 have proved inadequate in the writer's experience. 



Fio. 45. — Senna in Powder. 

 C. Crystals; H, hairs, large and small ; EP, epidermis, above, show- 

 ing scars of hairs; P, parenchyma; B, bast fibres; W, woody fibres; 

 AV, annular vessel; RV, reticular vessel; V, pitted vessel; X, epi- 

 dermis of leaf about a hair; Fib, fibres of phloem. 



The crystals are small and at times rare. Two types 

 are observ^able: flat tabular angular forms and the 

 spherical agglomerative variety. 



