174 PLANT ORGANS OR PARTS OF PLANTS. 



CORTEX VIBURNI PRUmFOLII. BLACK HAW. 



The bark of Viburnum prunifolium, Linne (nat. ord. 

 CaprijoliacecB) . 



This is a large shrub or small tree, 2.5 to 6 m. high, 

 growing in the eastern part of the United States from 

 Connecticut to Florida. The bark of both stem and root 

 is collected. 



Description. — The stem bark occurs in small, thin, 

 irregular, slightly curved pieces. Outer surface light 

 brown or with irregular patches of silvery white, and 

 blackish, much fissured cork, somewhat warty or showing 

 small black dots. Inner surface smooth, showing minute, 

 glistening crystals (calcium oxalate). The root bark is in 

 much more irregular pieces, lighter in color, outer 

 surface smoother, of an even grayish-brown color, inner 

 surface striated. Both varieties are very brittle. The 

 taste is bitter, more so in the root bark than in that of the 

 stem, and astringent. There is no odor. 



Histology. — The cork when present is formed of typical 

 flat tabular cells. The cortical parenchyma is made up of 

 tangentially elongated polyhedral cells rich in agglom- 

 erated crystals of calcium oxalate. Distributed through- 

 out are round or oval various sized groups of stone cells 

 with minute lumens and concentrically and radially 

 marked walls. The liber is formed of regularly arranged 

 radial lines of parenchyma. Fibres are absent, but, as in 

 the outer bark, calcium oxalate crystals and stone cells 

 are abundant. 



The many indistinct medullary rays one-cell wide, of 

 regular radially elongated cells, divide the inner bark 

 in narrow bands. 



Chemistry. — Two bitter resins have been isolated: 

 one brown, proved not to be of glycosidal nature; the 

 other greenish-yellow, slightly soluble in water, freely so 

 in alcohol (Kramer's viburnin). Valerianic acid or 



