PARTS OF ROOTS AND STEMS. 
171 
and also found growing in Europe and Asia. The 
cultivated variety is known as Snowball or Guelder- 
rose. 
Description. — In transversely curved pieces, 6 to 
20 cin. long, 1 to 2 cm. in diameter, 0 5 to T5 mm. 
thick ; outer surface light brown or brownish black, 
longitudinally wrinkled, periderm sometimes exfoli- 
ated revealing a nearly smooth reddish-brown surface, 
with numerous grayish patches of foliaceous lichens, 
and small brownish-black apothecia and large brown- 
ish lenticels; inner surface light or reddish brown, 
finely striate longitudinal^ ; fracture uneven, fibrous, 
surface light or reddish brown, with groups of stone 
cells and bast fibers; odor slight; taste astringent, 
bi tter. 
Constituents. — A bitter, somewhat resinous prin- 
ciple viburnin; valerianic (viburnic acid) and other 
organic acids; resin; tannin; calcium oxalate; ash 
about 10 per cent. 
XANTHOXYLUM (Prickly Ash Bark). 
The dried bark of Xantlioxylum Americanum (Fam. 
Rutaceee), a shrub or small tree indigenous from Que- 
bec to Virginia and west to South Dakota, Nebraska 
and Kansas. Southern Prickly Ash bark, which is 
also a source of the drug, is derived from Xanthoxylum 
C lava- Her cu/is, a shrub which is found south from Vir- 
ginia to Texas. The latter, however, appears to be less 
valuable medicinally. 
Description. — Northern Prickly Ash.— In transversely 
curved pieces, occasionally in single quills, 2 to 17 cm. 
long, 1 to 2 cm. in diameter, 0 5 to 3 cm. thick ; outer 
surface light brown to brownish black, with grayish 
patches of foliaceous lichens, numerous small black 
apothecia and whitish lenticels; fracture short, un- 
