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PH A RMA GO Gy OS Y. 
jections of bast fibers in the inner bark, the medullary 
rays one to two cells wide, forming converging groups; 
in cross section the inner surface of the bark indis- 
tinctly crenate; odor distinct; taste bitter, slightly acrid. 
Constituents. — Purshianin, a crystalline glucoside, 
which yields emodin ; chrysarobin; chrysopbanic acid; 
three resins; volatile and fixed oils; a bitter principle; 
tannin; starch and calcium oxalate. 
Adulterants. — Bhamnus Californica, a shrub indig- 
enous to Southern California and the neighboring 
States, yields a bark which closely resembles that of 
Rhamnus Purshiana, but may be distinguished from it 
by the medullary rays, which are from 3 to 5 cells wide, 
and occur in more or less parallel wavy rows, and by 
the distinct crenation of the inner margin of the bark. 
VIBURNUM PRUNIFOLIUM (Black Haw Bark). 
The dried bark of the root, stem and branches of 
Viburnum prunifolium (Fam. Caprifoliaceae), a shrub, 
indigenous to the Eastern and Central United States. 
The root bark is more highly esteemed than that of the 
stem and branches. 
Description. — Stem Bark. — In transversely curved 
pieces, or irregular oblong chips, P5 to 6 cm. long, 0'5 
to P5 cm. in diameter, 0 5 to l - 5 mm. thick ; outer sur- 
face brownish red or grayish brown, longitudinally 
wrinkled, periderm occasionally exfoliated, with occa- 
sional grayish patches of foliaceous lichens and numer- 
ous lenticels ; inner surface yellowish or reddish brown, 
longitudinally striate; fracture short, periderm brown- 
ish red, inner bark with numerous light-yellow groups 
of stone cells; odor slight; taste astringent and bitter. 
Root Bark. — Somewhat resembling the stem bark, but 
smoother externally, without lichens and having fewer 
lenticels. 
