262 



HISTOLOGY OF MEDICINAL PLANTS 



branched; therefore, large intercellular spaces occur between 

 the cells. 



Under Palisade Parenchyma. The palisade cells of the 

 under epidermis are short and broad, and they contain fewer 

 chlorophyll grains than the upper palisade cells of the upper 

 epidermis. These cells occur only under the veins. 



Under Hypodermis. The under hypodermal cells are shorter 

 and broader than the upper hypodermal cells. 



Under Epidermis. The under epidermal cells are modified 

 to form papillae which are similar to the papillae of the upper 

 epidermis. 



Fibro-Vascular Bundle. The cells composing the vascular 

 bundle are sieve cells, vessels, and fibres. 



The sieve cells are small and the walls are white and 

 angled. 



The vessels have thick, white, angled walls. 

 The bast fibres are rounded in outline and the walls are thick 

 and white. 



Endodermis. The endodermal cells encircle the fibro-vascu- 

 lar bundles. The cells are large, thin- walled, and oval in shape. 



Secretion Cells. Near the edges of the leaf are schizoge- 

 nous secretion cavities surrounded by thin- walled secretion 

 cells. 



POWDERED KLIP BTJCHU 



When the leaf is powdered (Plate 109), the cells are quite 

 as characteristic in appearance. The upper epidermal cells 

 (1) have thick-beaded, yellowish- white walls and papillate outer 

 walls. No stomata occur on the upper surface. The under 

 epidermis (2) with numerous stomata, is surrounded by the 

 characteristic guard cells. The end walls are beaded as on the 

 upper surface. The palisade cells (3) appear as in the cross- 

 section. The conducting cells (4 and 4) are of the spiral and 

 pitted type. The papillae (5 and 5) are very abundant in the 

 powder and very characteristic. The fragments of the epidermis 

 (6) are also abundant. The mesophyll (7) is characteristic, as 

 it retains its form when powdered. The fibres (8) are usually 

 associated with the conducting cells; occasionally they are 

 found free as in the illustration. 



