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PHARMACEUTICAL BOTANY 



Gross Structure and Histology of Different Types of Dorsoventral 

 Leaf Blades. i. Umbrophytic. Characterized by leave^ mostly 

 undivided and having the largest and most continuous leaf expanse. 

 Usually the deepest green leaves we have, to enable the leaves to 



FIG. 86. Transverse section through portion of dorsoventral leaf blade of 

 horehound (Marrubium vulgare). Upper epidermis devoid of stomata (up.ep.); 

 lower epidermis which possesses stomata (I. ep)\ palisade parenchyma (pal.); 

 spongy parenchyma (sp. p); xylem (x) and phloem (ph) regions of fibrovascular 

 tissue of stronger vein; long-pointed non-glandular trichome (t); branched tri- 

 chomes (ft 1 , ft z , ft 3 ); several types of glandular trichomes (gt, gt 2 , gt s , gl 4 ). 



absorb scattered and reduced rays that pass in through high trees 

 and shrub overhead. Their texture is usually thin and soft. In 

 microscopic structure they are covered with a cutinized epidermis 

 which has all the stomata on the lower surface. The mesophyll is 

 fairly spongy, the spongy parenchyma having decided intercellular 



