80 LEAVES. 



(44) Sage Leaves. 



The leaves of Salvia ojfficinalis, Linne (N.O. Labiatae). 



The upper epidermis is composed of cells with slightly undulating 

 walls ; on the lower surface they are rather more sinuous. Both 

 surfaces are provided with stomata as well as with simple and 

 glandular hairs. 



The stomata are enclosed between two crescent-shaped cells at 

 right angles to the ostiole ; this arrangement is common in labiate 

 leaves. 



The simple hairs are usually long and undulating; they are 

 composed of two or three cells, the terminal one gradually tapering 

 to a whip-like point. 



The glandular hairs vary in structure. Some consist of a 

 unicellular rounded gland, supported upon a unicellular or bi- 

 cellular pedicel ; in others the gland is large, octocellular and 

 sessile. The mesophyll is heterogeneous and devoid of crystals ; 

 the midrib is concavo-convex, and there are no lignified element 

 in either bast or pericycle. 



The diagnostic characters of powdered sage leaves are : 



(a) The position of the stomata. 



(b) The characteristic hairs and glands* 



(c) The absence of calcium oxalate crystals. 



(d) The absence of pericy die fibres. 



