Wolf's Bane

Appearance

"Arnica montana" is a flowering plant about 18–60 cm tall aromatic fragrant, herbaceous perennial. Its basal green ovate leaves with rounded tips are bright coloured and level to the ground. In addition, they are somewhat downy on their upper surface, veined and aggregated in rosettes. By contrast, the upper leaves are opposed, spear-shaped and smaller which is an exception within the Asteraceae. The chromosome number is 2n=38.

The flowering season is between May and August. The hairy flowers are composed of yellow disc florets in the center and orange-yellow ray florets at the external part. The achenes have a one-piece rough pappus which opens in dry conditions. "Arnica montana" is a hemicryptophyte, which helps the plant to survive the extreme overwintering condition of its habitat. In addition, "Arnica" forms rhizomes, which grow in a two-year cycle: the rosette part grows at its front while its tail is slowly dying.

Distribution

"Arnica montana" is widespread across most of Europe. It is absent from the British Isles and the Italian and Balkan peninsulas. In addition, it is considered extinct in Hungary and Lithuania.

Habitat

"Arnica montana" grows in nutrient-poor siliceous meadows or clay soils. It mostly grows on alpine meadows and up to nearly 3,000 m. In more upland regions, it may also be found on nutrient-poor moors and heaths. However Arnica does not grow on lime soil, thus it is an extremely reliable bioindicator for nutrient poor and acidic soils. 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 and commercial wild-crafting. Nevertheless, it is cultivated on a large scale in Estonia.

Defense

The US Food and Drug Administration has classified "Arnica montana" as an unsafe herb because of its toxicity. It should not be taken orally or applied to broken skin where absorption can occur. Arnica irritates mucous membranes and may elicit stomach pain, diarrhea, and vomiting. It may produce contact dermatitis when applied to skin.

"Arnica montana" contains the toxin helenalin, which can be poisonous if large amounts of the plant are eaten or small amounts of concentrated Arnica are used. Consumption of "A. montana" can produce severe gastroenteritis, internal bleeding of the digestive tract, raised liver enzymes, nervousness, accelerated heart rate, muscular weakness, and death if enough is ingested. Contact with the plant can also cause skin irritation. In the Ames test, an extract of "A. montana" was found to be mutagenic.