ARNICA 



337 



FIG. 174. Arnica rhizome. Natural size. 

 (Holmes.) 



Description. The rhizome, which is horizontal or oblique, is 

 slender, nearly cylindrical in shape, and usually curved. It averages 

 about 5 cm. in length and 

 about 5 mm. in thickness, and 

 varies in colour from yellowish 

 brown to nearly black. From 

 the flanks and under surface 

 numerous dark, brittle, wiry 

 curved and twisted roots about 

 8 cm. in length are given off, 

 and the scars that are left, 

 when these break off or perish, 

 together with the encircling 

 scars of cataphyllary leaves, 

 render the surface of the rhi- 

 zome, which is in addition 



longitudinally shrivelled, distinctly rough. Usually it is simple and 

 often terminated by the hairy remains of leaves ; sometimes, 

 after the plant has flowered, the growth of the rhizome, which 

 has thus been terminated, is continued in the same direction by the 

 development of a bud on its under surface ; the rhizome thus formed 

 will in due course itself flower, and the further growth will again 

 be ensured by the development of one of the lower buds. Thus 



the rhizome occasionally 

 assumes a jointed appear- 

 ance. 



The rhizome breaks with 

 a short fracture, and is often 

 discoloured in the interior. 

 The transverse section of a 

 favourable specimen shows 

 a comparatively thick 

 whitish or yellowish bark, 

 in which near the wood is a 

 circle of darker oleo-resin 



P V,-, ducts - The wood consists 



of yellow wedge-shaped 

 wood-bundles and broad 

 medullary rays enclosing 

 a large whitish pith which 

 in longitudinal sections is 

 seen to be continuous. 

 The root also shows a thick 



white bark with a ring of oleo-resin ducts and a yellowish wood. 

 The drug has a faint but rather agreeable apple-like odour and 

 a bitter acrid taste. 



22 



FIG. 175. Arnica rhizome. Transverse sec- 

 tion of rhizome, v, bast ; o, primary 

 cortex ; y, wood-bundles ; r, medullary 

 rays ; c, pith ; p, oleo-resin ducts. Mag- 

 nified 10 diam. (Berg.) 



