442 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



more or less coriaceous; odor agreeable; aromatic; taste pleasantly 

 bitter and astringent. 



Inner Structure. Tea leaves are distinguished from most other 

 leaves by their large colorless stone cells or idioblasts, which frequently 

 extend from the upper to the lower surfaces of the leaf. They vary 

 in form and size, usually have very irregular walls and are somewhat 

 branched. 



Powder. Dark green; large, elongated, irregular and colorless 

 stone cells (idioblasts) ; numerous unicellular, long, thick-walled, non- 

 glandular hairs 0.010 mm. in width; rosette aggregates of calcium 

 oxalate about 0.010 mm. in diameter; characteristic stomata 0.030 

 to 0.060 mm. in diameter, with 3 or 4 accompanying cells. Adulter- 

 ants are distinguished by possessing chiefly other forms of calcium 

 oxalate crystals and hairs. 



ALLIED PLANT. Mate or Paraguay tea is distinguished by the 

 stomata, which are much larger than the epidermal cells of the lower 

 surface; the epidermal cells occurring near the veins are in nearly 

 parallel rows and have a striated cuticle; sclerenchymatous fibers 

 are associated with the tracheae, and calcium oxalate occurs in rosette 

 aggregates. 



Adulterants. Ash leaves (species of Fraxinus) have rather 

 characteristic "horned" stomata, due to the increased thickening 

 of the cutinous layers at the openings of the stomata; the epider- 

 mal cells are very wavy in outline. CAMELLIA leaves contain idio- 

 blasts (similar to those in tea leaves) and calcium oxalate crystals, 

 but the lower epidermis is thick-walled and more or less papillose. 

 CHERRY leaves (Prunus avium) have numerous small rosette 

 aggregates of calcium oxalate in the lower epidermal cells. GROM- 

 WELL leaves (Lithospermum officinale) have stiff, scythe-shaped 

 hairs with centrifugal thickening of cuticle. MAPLE leaves (Acer 

 Negundo) have non-glandular and glandular hairs, the latter with a 

 2- to 3-celled stalk and large, unicellular head. MEADOW-SWEET 

 (Spiraea Ulmaria) has unicellular, thin-walled, non-glandular hairs, 

 the basal walls of which are truncate; the glandular hairs have either 

 a 3-celled or multicellular stalk and a large, multicellular head. 

 MOUNTAIN ASH or European Rowan (Sorbus Aucuparia) possesses 

 long, thin-walled, non-glandular hairs with rounded bases. MUL- 

 BERRY leaves (Morus alba and M. nigra) have cystoliths in epidermal 

 cells, non-glandular and glandular hairs, the latter with a unicellular 

 stalk and 5- to 9-celled head. OAK leaves (Quercus pedunculata and 

 Q. sessilflora) have 2- to 3-celled, non-glandular hairs and stomata 

 only on epidermis of lower surface. SLOE leaves (Prunus spinosa) 



