Distribution and habitat 
Arnica montana is endemic to Europe, from southern Iberia to southern Scandinavia and the Carpathians. It is absent from the British Isles and the Italian and Balkan Peninsulas. A. montana grows in nutrient-poor siliceous meadows up to nearly 3,000 metres (9,800 ft). It is rare overall, but may be locally abundant. It is becoming rarer, particularly in the north of its distribution, largely due to increasingly intensive agriculture. In more upland regions, it may also be found on nutrient-poor moors and heaths.
A. montana has tall stems, 20–60 centimetres (7.9–24 in) high, supporting usually a single flower head. Most of the leaves are in a basal rosette, but one or two pairs may be found on the stem and are, unusually for composites, opposite. The flower heads are yellow, approximately 5 cm in diameter, and appear from May to August.
Uses and toxicity 
Arnica montana is sometimes grown in herb gardens and has long been used medicinally. It contains the toxin helenalin, which can be poisonous if large amounts of the plant are eaten. It produces severe gastroenteritis and internal bleeding of the digestive tract if enough material is ingested. Contact with the plant can also cause skin irritation. The roots contain derivatives of thymol, which are used as fungicides and preservatives and may have some anti-inflammatory effect. When used topically in a gel at 50% concentration, Arnica montana was found to have the same effect when compared to a 5% ibuprofen gel for treating the symptoms of hand osteoarthritis.
A scientific study found that the application of topical arnica had no better effect than a placebo in the treatment of laser-induced bruising.
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- Gregory L. Tilford (1997). Edible and Medicinal Plants of the West. Mountain Press. ISBN 0-87842-359-1.
- "Poisonous Plants: Arnica montana". North Carolina State University.
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- I. Weremczuk-Jezyna, W. Kisiel & H. Wysokińska (2006). "Thymol derivatives from hairy roots of Arnica montana". Plant Cell Reports 25 (9): 993–6. doi:10.1007/s00299-006-0157-y. PMID 16586074.
- P. C. Braga, M. Dal Sasso, M. Culici, T. Bianchi, L. Bordoni & L. Marabini (2006). "Anti-inflammatory activity of thymol: inhibitory effect on the release of human neutrophil elastase". Pharmacology 77 (3): 130–6. doi:10.1159/000093790. PMID 16763380. Retrieved January 27, 2008.
- R. Widrig, A. Suter, R. Saller & J. Melzer (2007). "Choosing between NSAID and arnica for topical treatment of hand osteoarthritis in a randomised, double-blind study". Rheumatology International 27 (6): 585–91. doi:10.1007/s00296-007-0304-y. PMID 17318618.
- Delilah Alonso, Melissa C. Lazarus & Leslie Baumann (2002). "Effects of topical arnica gel on post-laser treatment bruises". Dermatologic Surgery 28 (8): 686–8. doi:10.1046/j.1524-4725.2002.02011.x. PMID 12174058. Retrieved January 27, 2008.
|Wikimedia Commons has media related to: Arnica montana|
- Royal Society of Medicine Article concerning testing involving Arnica (RSM)
- Botanica.com Arnica
- "Arnica montana". Integrated Taxonomic Information System. Retrieved May 23, 2006.