552 



BOTANY AND PHARMACOGNOSY. 



brown, finely striate, glandular-pubescent and surmounted by a 

 pappus of white barbed bristles about 7 mm. long; odor distinct; 

 taste bitter and acrid. 



Constituents. — A bitter crystalline principle, arnicin, about 4 

 per cent. ; and volatile oil 0.04 to 0.07 per cent, consisting of a 

 butyraceous substance. 



Adulterants. — Arnica flowers are not infrequently adulter- 

 ated with the flowers of various other Compositae, or even entirely 

 substituted by them ; of these may be mentioned the flowers of 

 Calendula officinalis (see Calendula) ; species of Inula, the akenes 



Fig. 241. Arnica florets; A, overlapping hairs of pappus considerably magnified; 

 B, ray floret; C, disk floret. AC. inferior ovary becoming in fruit an akene; PA, pappus; 

 P, corolla; A, anthers; Y, style; T, stigma. 



of which are glabrous ; and Tragopogon pratensis, the ligulate 

 florets of which are 5-toothed at the apex. 



Allied Drugs. — The rhizome and roots of Arnica montana 

 are official in a number of pharmacopoeias. The rhizome is 

 oblique, about 5 cm. long and 3 mm. thick, the upper portion with 

 buds or stem-remnants, externally dark brown, longitudinally 

 wrinkled and irregularly annulate, with numerous light brown, 

 fragile roots which may be 10 cm. long; fracture short, bark 

 rather thick, with a single circle of large resin canals. The drug 

 contains the bitter principle arnicin, which is also found in the 

 flowers; and a volatile oil, 0.5 to o.i per cent., with a radish-like 

 odor and consisting of hvdrothymoquinone methyl ether, phloryl 



