Source, Etc

Black haw bark is the root-bark of Viburnum pruni-folium, Linne (N.O. Caprifoliaceoe), a shrub indigenous to the eastern and central United States.

Description

The drug occurs in short, quilled, channelled or curved pieces from 1 to 4 mm. (usually about 2 or 3 mm.) in thickness, and of a dull brown or reddish brown colour. In the youngest pieces the outer surface is slightly longitudinally wrinkled, older pieces exhibit small, rounded, or oval lenticels, while in old bark the surface is irregularly wrinkled, fissured, and scaly. Inner surface longitudinally striated, rough and reddish brown. Fracture short and granular, the fractured surface exhibiting a dark brown cork and a whitish or reddish cortex and bast, in which numerous pale yellowish groups of sclerenchymatous cells are distinguishable. The odour is slight, the taste bitter and astringent. Portions of the smaller roots often occur in the drug.

The student should observe

(a) The dull outer surface,

(b) The granular fracture,

(c) The bitter taste; and should compare the bark with

(i) Wild Cherry bark, which has a glossy outer surface, (ii) Pale Cinchona Bark, which has a more fibrous fracture and (usually) rougher surface.

Constituents

Black haw bark contains viburnin (a water-soluble bitter glucoside), tannin, and a little resin.

Uses

The drug has been used for dysmenorrhoea and asthma it is supposed to prevent threatened abortion and to check haemorrhage.