Arnica

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Arnica L. is a genus with about 30 perennial species, belonging to the sunflower family (Asteraceae).

This circumboreal and montane genus occurs mostly in the temperate regions of North America, while two are native to Eurasia.

Arnica used to be included in the tribe Senecioneae, because it has a pappus of fine bristles. This was soon questioned and Nordenstam (1977) placed it tentatively in tribe Heliantheae s.l. This arrangement became also uncertain because of the sesquiterpene lactone chemistry in certain species. Lately Arnica was placed in an unresolved clade together with Madiinae, Eupatorieae, Heliantheae s.s. and Pectidinae.

Leaves : opposite leaves borne towards the apex of the stem.

Flower : each phyllary (= a bract under the flowerhead) is associated with a ray floret. Species of Arnica, with an involucre (= a circle of bracts arranged surrounding the flower head) arranged in two rows, have only their outer phyllaries associated with ray florets.

Fruit : pappus of plumose bristles.

Uses : several species, such as Arnica montana and Arnica chamissonis contain helenalin, a sesquiterpene lactone that is a major ingredient in anti-inflammatory prepatations (mostly against bruises).

Species

• Arnica acaulis (Walt.) B.S.P. -- Common Leopardbane
• Arnica alpina (L.) Olin -- Alpine Arnica
• Arnica amplexicaulis Nutt. -- Clasping Arnica, Streambank Arnica
• Arnica angustifolia Vahl -- Narrowleaf Arnica
• Arnica cernua T.J. Howell -- Serpentine Arnica
• Arnica chamissonis Less. -- Chamisso Arnica
• Arnica cordifolia Hook. -- Heart-leaf Leopardbane, Heartleaf Arnica
• Arnica dealbata Baldwin (formerly Whitneya dealbata)
• Arnica discoidea Benth. -- Rayless Arnica
• Arnica X diversifolia Greene (pro sp.) -- Curtis Churchmouse Threeawn, Rayless Arnica, Sticky Arnica
• Arnica frigida C.A. Mey. ex Iljin -- Snow Arnica
• Arnica fulgens Pursh -- Foothill Arnica, Orange Arnica, Shining Leopardbane
• Arnica x gracilis Rydb. -- Smallhead Arnica (a natural hybrid between A. latifolia and A. cordifolia)
• Arnica lanceolata Nutt. -- Arnica, Lanceleaf Arnica
• Arnica latifolia Bong. -- Broadleaf Arnica
• Arnica lessingii (Torr. & Gray) Greene -- Nodding Arnica
• Arnica lonchophylla Greene -- Longleaf Arnica
• Arnica longifolia D.C. Eat. -- Longleaf Arnica, Spearleaf Arnica
• Arnica louiseana Farr -- Lake Louise Arnica
• Arnica mallotopus (formerly Mallotopus japonicus)
• Arnica mollis Hook. -- hairy arnica, wooly arnica
• Arnica montana L. -- Mountain Arnica
• Arnica nevadensis Gray -- Nevada Arnica
• Arnica parryi Gray -- Nodding Arnica, Parry's Arnica
• Arnica rydbergii Greene -- Rydberg Arnica, Rydberg's Arnica, Subalpine Arnica
• Arnica sororia Greene -- Twin Arnica
• Arnica spathulata Greene -- Klamath Arnica
• Arnica unalaschcensis Less. -- Alaska Arnica
• Arnica venosa Hall -- Shasta County Arnica
• Arnica viscosa Gray -- Mt. Shasta Arnica

Reference

• Wolf, S.J. & K.E. Denford. 1984. Taxonomy of Arnica (Compositae) subgenus Austromontana. Rhodora Journal of the New England Botanical Club 86(847): 239 - 309.
• Nordenstam, B. 1977 Senecioneae and Liabeae—systematic review. In V. H. Heywood, J. B. Harborne, and B. L. Turner [eds.], The biology and chemistry of the Compositae, vol. II, 799–830. Academic Press, London, UK

Gallery

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  Mountain Arnica (Arnica montana)
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  Mountain Arnica (Arnica montana)
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  Longleaf Arnica (Arnica longifolia)