MICROSCOPICAL EXAMINATION OF POWDERED VEGETABLE DRUGS 97 



I 2 Epidermis. See above. 



2 2 Cork cells. 



3 2 Parenchyma with cell-contents, as starch, crystals, resin, 



coloring matter, etc. 



4 2 Stone cells (sclerenchyma) . Sometimes diagnostic. 

 5 2 Vascular tissue. 



I 3 Bast. 



2 3 Tracheids. 



3 3 Vessels. Occasionally characteristic. 



I 



II. FLOWERS. 



I 1 Staminate structures. 



I 2 Vegetative tissue elements. Not characteristic, diagnostic or 



distinct. 



2 2 Pollen grains. Very important and diagnostic. 

 I 3 Size. Not very variable. 

 2 3 Form. Quite variable and characteristic. 

 3 3 Color. Mostly yellowish brown. 

 4 3 Markings of exine. Characteristic and diagnostic. 

 2 1 Pistillate structures. Not diagnostic. 

 3 1 Petals. 



I 2 Epidermal elements. Compare with leaf. 

 I 3 Structure and form. Hair cells. 

 2 3 Contents. Coloring matter. 

 2 2 Parenchyma. Deficient and not important. 

 3 2 Vascular tissue. Deficient and not diagnostic. (See leaf.) 

 4 1 Sepals. Compare with leaf. Quite important. 

 5 1 Pappus. Often diagnostic. 



6 1 Stone cells. Usually from torus. Quite important and char- 

 acteristic. 



III. FRUITS AND SEEDS. 



I 1 Epidermal elements. Special modifications of cells, often very 

 characteristic and diagnostic. Compare with 

 leaf. 



I 2 Hair cells. Usually nonglandular and characteristic. 

 2 2 Stomata. Rare and not important. 

 2 1 Stone cells. Usually present. Often diagnostic. 

 I 2 Form and size. Variable. 

 2 2 Color. Reddish brown to nearly colorless. 

 3 2 Cell-walls. 

 I 3 Porosity. 

 2 3 Thickness. 



