794 MANUAL OF POISONOUS PLANTS 



smooth and green above, but quite woolly underneath; pinnatifid, the divisions 

 cut-toothed, linear-lanceolate; heads small in open leafy panicles. 



Distribution. In waste places from Canada to North Carolina to Penn- 

 sylvania and occasionally westward. 



Poisonous properties. The common mugwort was used medicinally by the 

 physicians of the 16-18 century, but in modern times the plant is not used to 

 any extent. Mugwort causes epileptic spasms, profuse sweat with the odor 

 of garlic; violent contractions of the uterus; labor-like pains; prolapsus and 

 rupture of the uterus; miscarriage; metrorrhagia and increase of lochial dis- 

 charges. 



24. Arnica L. 



Perennial herbs, erect, simple or branching; leaves opposite, or rarely with 

 the upper alternate; heads many-flowered, radiate on long peduncled heads; 

 scales of the involucre bell-shaped; bracts in 1-2 series; the ray flowers pistil- 

 late and fertile; disk flowers perfect and fertile; achenes linear, 5-10 ribbed; 

 pappus of roughened-denticulate bristles. 



About 30 species native to the Northern Hemisphere. The tincture of arnica 

 is a well-known house remedy used for bruises and chilblains. A. montana 

 contains a bitter principle arnicin C, () H 38 O 4 . The value of arnica as a germicide 

 has been largely overestimated. The germicidal action is probably due to the 

 presence of alcohol. Dr. White, in his Dermatitis Venenata, records several in- 

 stances of injurious effects from the use of arnica. In one case a gentleman 

 descending the stairs to mount his horse for a ride, slipped and scraped the 

 lower part of his back. A handkerchief dipped in the tincture was applied to 

 the bruised skin and worn in contact with the part during the ride. During 

 the ride he felt considerable itching and upon his return home found that the 

 skin was greatly congested. On the next day I was called to see him. The 

 skin of the back, nearly to the shoulders, was in a state of active hyperaemia, 

 and already covered with innumerable papules. The inflammatory process ex- 

 tended rapidly downwards nearly to the knees, and forward upon the abdomen 

 and genitals. In a few days these parts presented all the characteristic ap- 

 pearances of acute eczema in its various stages of progression : general hyper- 

 aemia, papules, vesicles, excoriated and exuding surfaces, and crusts. The 

 subjective symptoms were intense itching, stinging, and burning in the parts. 

 Scarcely any clothing could be borne in contact with the skin by day, and sleep 

 was for a few nights almost impossible, but the system generally was only 

 slightly disturbed. Dr. White records two other cases. All three seem to 

 have been old gentlemen and he states: "In all of them we have an acute in- 

 flammatory process, confined to the upper dermal layers, and manifesting itself, 

 according to the stage reached, by the following appearances : hyperaemia, 

 papules, vesicles, excoriations, crusts, and scales, in regular sequence. The local 

 sensations were intense itching and some degree of burning in the parts af- 

 fected." 



Arnica cordifolia Hook. Arnica 



A low perennial, 1-2 ft. high or less; pubescent, or the stem hirsute and 

 peduncles villous; the root and leaves deeply cordate or ovate at the base, on 

 slender petioles; stem leaves opposite, in 1-3 pairs, dentate or denticulate; upper 

 small, sessile; heads few, solitary; involucre pubescent or villous; rays an inch 

 long; achenes mere or less hirsute. 



