Arnica montana, also known as wolf's bane, leopard's bane, mountain tobacco and mountain arnica,[4] is a moderately toxic European flowering plant in the daisy family Asteraceae that has a large yellow flower head.

Arnica montana has been used as a herbal medicine, but there is insufficient clinical evidence for its therapeutic use, and it is toxic when taken internally or applied to injured skin.

[5] Arnica montana is a flowering plant about 18–60 cm (7.1–23.6 in) tall aromatic fragrant, herbaceous perennial.

Its basal green ovate leaves with rounded tips are bright coloured and level to the ground.

[6][7] Arnica montana is a hemicryptophyte,[8] which helps the plant to survive the extreme overwintering condition of its habitat.

It is becoming rarer, particularly in the north of its distribution, largely due to increasingly intensive agriculture and commercial wildcrafting (foraging).

[12] The main constituents of Arnica montana are essential oils, fatty acids, thymol, pseudoguaianolide sesquiterpene lactones and flavanone glycosides.

[15] 2,5-Dimethoxy-p-cymene and thymol methyl ether are the primary components of essential oils from both the plant's roots and rhizomes.

[16] The quality and chemical constitution of the plant substance Arnicae flos can be monitored by near-infrared spectroscopy.

[21] The US Food and Drug Administration has classified Arnica montana as an unsafe herb because of its toxicity.

[citation needed] The plant is rare; it is protected in Belgium, France, Germany, Italy, Poland, and in some regions of Switzerland.