Classification (APG IV)
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Arnica
Species: Chamisso arnica - Arnica chamissonis L.

Botanical Description
Chamisso arnica (Arnica chamissonis) is a perennial plant from the Asteraceae family, growing between 20–80 cm (up to 150 cm) in height. The stem is usually branched from the middle or upper part. The plant has 4–10 pairs of leaves, evenly distributed along the stem. Basal leaves appear in 1–2 pairs and have short petioles, though some leaves may be sessile. The leaves are lanceolate, oval, or elongated, measuring 5–20 × 2–6 (8) cm. The margins can be entire or remotely serrated to distinctly toothed. The leaf tips are pointed, and the surfaces range from nearly glabrous to densely covered in white woolly hairs.

The plant produces 3–10 (up to 16) flower heads. The involucre is bell-shaped, sometimes hemispherical. The phyllaries (involucral bracts) number between 8 and 23 and are narrowly lanceolate, each tipped with a distinctive tuft of white hairs. There are 8–20 ray florets, with yellow corollas featuring two notches at the tips. The disk florets also have yellow corollas and yellow anthers. The seeds are gray to brown, measuring 3–8 mm, nearly glabrous to sparsely hairy. The pappus hairs are straw-colored and feathery. [1,2]

Distribution
Chamisso arnica prefers growing in western North America, predominantly in Canada. The plant is commonly found in meadows and pastures, where it can form large populations. [3]

Effects and Uses
Chamisso arnica shares a similar chemical composition with Arnica montana, a species widely used in pharmaceuticals and cosmetics but endangered and endemic to Europe. [3]

The pharmacological properties of Chamisso arnica are primarily attributed to the presence of essential oils in the flower heads. Key components include α-pinene, cumene, p-cymene, germacrene D, spathulenol, decanal, caryophyllene oxide, β-pinene, and benzylacetaldehyde. These compounds contribute to the plant’s anti-inflammatory, radical-scavenging, and antioxidant effects, which may help in preventing or slowing diseases caused by free radicals. [4-6]

Arnica, including Chamisso arnica, is commonly used in various topical formulations such as creams, extracts, and tinctures. These preparations are applied externally for relieving muscle pain, inflammation, and soreness. They are also used for sunburns, minor burns, diaper rash, sprains, insect bites, gingivitis, and rheumatic discomfort. Arnica is a key ingredient in homeopathic medicine, where it is frequently included in creams and gels to alleviate bruising and muscle pain. It has limited applications in hair tonics and anti-dandruff treatments. [4-6]

References
1. Small, U., Catling, P. M. (1999). Canadian Medicinal Crops. NRC Research Press.
2. Quattrocchi, U. (2016). CRC World Dictionary of Medicinal and Poisonous Plants. CRC Press.
3. Sugier, D., Olesińska, K., Sugier, P., & Wójcik, M. (2019). Chemical Composition of Essential Oil from Flower Heads of Arnica chamissonis Less. under a Nitrogen Impact. Molecules (Basel, Switzerland), 24(24), 4454. https://doi.org/10.3390/molecules24244454
4. Chemical Composition of Essential Oil from Flower Heads of Arnica chamissonis Less. under a Nitrogen Impact - PubMed. (2023). PubMed. Retrieved from https://pubmed.ncbi.nlm.nih.gov/
5. Antioxidant properties of Chamisso arnica (Arnica chamissonis Less.) water infusions – DOAJ. (2023). DOAJ. Retrieved from https://doaj.org/
6. Arnica | Medicine Hunter. (n.d.). Medicine Hunter. Retrieved from https://www.medicinehunter.com/arnica

Süstemaatiline kuuluvus (APG IV)
Riik: Taimed (Plantae)
Klaad: Soontaimed (Tracheophyta)
Klaad: Katteseemnetaimed (Angiospermae)
Klaad: Päriskaheidulehelised (Eudicotyledonae)
Selts: Astrilaadsed (Asterales)
Sugukond: Korvõielised (Asteraceae)
Perekond: Arnika (Arnica)
Liik: Chamisso arnika - Arnica chamissonis ssp. foliosa

Botaaniline kirjeldus
Chamisso arnika on mitmeaastane korvõielide taim, mis kasvab 20–80 (150) cm kõrguseks. Vars on tavaliselt keskelt või ülaosast hargnev. Lehti on 4–10 paari. Lehed varrel on ühtlaselt jaotunud. Juurmised lehed esinevad 1–2 paarina ja neil on lühike leheroots (esineb ka rootsuta lehti) Lehed on istuvad, kõige alumisel paaril on membraansed, kokkukasvanud, tupe-sarnased alused. Lehelabad on lantsetjad, ovaalsed või piklikud, 5–20 X 2–6 (8) cm suurused. Servad võivad olla terved või kaugelt hambulised kuni selgelt hambulised. Lehtede tipud on teravad, pinnad peaaegu paljad või karvadega kaetud kuni tihedalt valge-vildiste-karvastega. Õisikuid on 3–10 (16). Õisikukatted (involukraadid) on kellukakujulised, harvem poolkerakujulised. Phüllare (õisiku ümbrislehti) on 8–23, peaaegu lineaarsed kuni kitsalt lantsetjad, igaühe tipus silmatorkava valge karvatutiga. Keelõisi on 8–20, kroonlehed kollased, kahe täkkega otstega. Putkõite kroonlehed on kollased, tolmukad kollased. Seemned on hallid kuni pruunid, 3–8 mm, peaaegu paljad kuni hõredalt karvased. Pappuse karvad on õlekollased ning sulgjad. [1,2]

Levila
Arnika eelistab kasvada Põhja-Ameerika lääne osas, valdavalt Kanadas. Taime võib leida kasvamas niitudel ja karjamaadel. Võib esineda väga suurte populatsioonidena. [3]

Toime ja kasutamine
Chamisso arnika keemiline koostis sarnaneb mägiarnika (Arnica montana) omaga, mis on laialdaselt kasutusel farmaatsias ja kosmeetikas. Viimane on ohustatud ja endeemne liik Euroopas. [3]

Chamisso arnika farmakoloogilised omadused on peamiselt seotud oluliste eeterlike õlide sisalduse ja koostisega õisikes. Oluliste komponentide seas leiti alfa-pineeni, kumeeni, p-tsümeeni, germakreeni D, spathulenooli, dekanaali, karüofülleeni oksiidi, beeta-pineeni ja benseenatsetaldehüüdi. Need ained omavad olulist farmakoloogilist väärtust, aidates kaasa taime põletikuvastasele, antiradikaalsele ja antioksüdantsele omadustele, mis võivad olla kasulikud vabade radikaalide poolt põhjustatud haiguste ennetamisel või aeglustamisel. [4-6]

Üldiselt kasutatakse arnikat, sealhulgas Chamisso arnikat, erinevates preparaatides nagu kreemides, tõmmistes ning tinktuurides, välispidiseks kasutusteks, sealhulgas valulike lihaste, valu ja põletiku leevendamiseks. Neid preparaate kasutatakse ka päikesepõletuste, pindmiste põletuste, mähkmelööbe, nikastuste, põletikuliste putukahammustuste, igemepõletiku ja reumaatilise ebamugavuse paikseks leevendamiseks. Arnika on oluline ravim homöopaatias ja seda kasutatakse tavaliselt kreemides ja geelides, et leevendada verevalumeid ja lihasvalu. Samuti leiab see piiratud kasutust juuksetoonikutes ja kõõmavastastes preparaatides. [4-6]

Kasutatud kirjandus
1.Small, U., Catling, P. M. (1999). Canadian Medicinal Crops. NRC Research Press.
2.Quattrocchi, U. (2016). CRC World Dictionary of Medicinal and Poisonous Plants. CRC Press.
3.Sugier, D., Olesińska, K., Sugier, P., & Wójcik, M. (2019). Chemical Composition of Essential Oil from Flower Heads of Arnica Chamissonis Less. under a Nitrogen Impact. Molecules (Basel, Switzerland), 24(24), 4454. https://doi.org/10.3390/molecules24244454 
4. Chemical Composition of Essential Oil from Flower Heads of Arnica Chamissonis Less. under a Nitrogen Impact - PubMed. (2023). PubMed. Võetud aadressilt https://pubmed.ncbi.nlm.nih.gov/
5. Antioxidant properties of Chamisso arnica (Arnica chamissonis Less.) water infusions – DOAJ. (2023). DOAJ. Võetud aadressilt https://doaj.org/
6. Arnica | Medicine Hunter. (n.d.). Medicine Hunter. Võetud aadressilt https://www.medicinehunter.com/arnica