The Jepson Herbarium
		University of California, Berkeley

Directory       News       Site Map       Home

Perennial herb, generally from long, naked rhizome. Leaf: basal 0 or generally withered by flowering, or present as sterile rosettes; cauline opposite. Inflorescence: heads radiate or discoid (radiant), 1–many in ± flat-topped clusters; generally erect in bud (nodding); involucre hemispheric to obconic; phyllaries generally in 2 ± equal series; receptacle ± flat, epaleate. Ray flower: 0 or 5–22; ray yellow or yellow-orange. Disk flower: many, generally bisexual; corolla generally soft-hairy, generally colored like rays; anther tip triangular; style branches flat, tips truncate, short-hair-tufted. Fruit: ± cylindric, 5–10-veined; pappus (0 or) of many barbed to ± plumose bristles, white to red-brown.
29 species: North America, Eurasia. (Latin or Greek: ancient name) [Wolf 2006 FNANM 21:366–377] Diploid species sexual; polyploid species generally form seeds asexually.

Key to Arnica

1. Pappus 0 ..... A. dealbata

1' Pappus of 10–50 fine bristles

2. Heads discoid, some marginal flowers occasionally with ± expanded corollas

3. Leaves widely ± sessile

4. Leaf toothed, net-veined abaxially between 3–5 prominent veins; corolla yellow; fruit hairy, nonglandular ..... A. venosa

4' Leaf ± entire, weakly 3–5-veined; corolla cream; fruit stalked-glandular ..... A. viscosa

3' Proximal and middle leaves narrowed to a ± widely winged petiole (except Arnica discoidea, proximal leaves ± narrowly wing-petioled)

5. Phyllaries linear to lanceolate; young heads generally nodding; pappus brown-yellow, ± plumose ..... A. parryi (2)

5' Phyllaries narrowly lanceolate to lance-ovate; young heads erect; pappus white, generally short-barbed

6. Most proximal leaf blades lanceolate to ovate or ± cordate; petiole narrow, ± narrowly winged; fruit hairy and stalked-glandular ..... A. discoidea

6' Most proximal leaf blades ± oblanceolate; petiole ± widely winged; fruit sparsely stalked-glandular, generally otherwise glabrous ..... A. spathulata

2' Heads radiate

7. Cauline leaves generally 5–12 pairs, ± equal or gradually reduced distally on stem; heads 3–20

8. Phyllaries generally ± obtuse, adaxial face of tip generally hair-tufted; tube of disk corolla generally 3–4.5 mm ..... A. chamissonis

8' Phyllaries ± acute, tip ± no more hairy than body; tube of disk corolla generally 2–3 mm

9. Stems 1–few from short rhizome or caudex; leaves ± toothed ..... A. lanceolata subsp. prima

9' Stems clustered on short caudex-like rhizome; leaves ± entire ..... A. longifolia

7' Cauline leaves generally 2–4(6) pairs, often strongly reduced distally on stem; heads generally < 5(15)

10. Pappus (yellow-)brown, bristles ± plumose — rhizome short, freely rooting

11. Rays < 15 mm; proximal herbage ± long-spreading-hairy; young heads generally nodding ..... A. parryi (2)

11' Rays generally 15–25 mm; proximal herbage becoming glabrous to hairy or glandular; young heads erect

12. Heads spreading-bell-shaped to hemispheric; cauline leaves variable, ± sessile, most proximal generally largest ..... A. mollis

12' Heads ± narrowly obconic; cauline leaf blades elliptic to widely deltate, at least some petioled, middle generally largest ..... A. ovata

10' Pappus ± white to straw-colored, bristles short-barbed, if bristles ± plumose, rhizome long

13. Leaf blade narrow, length ± 3–6+ × width; basal leaves generally densely clustered; rays yellow-orange

14. Proximal axils brown-woolly-tufted; disk corollas spreading-hairy, stalked-glandular ..... A. fulgens

14' Proximal axils glabrous or sparsely white-hairy; disk corollas stalked-glandular only ..... A. sororia

13' Leaf blade generally ± wide, length generally < 2.5 × width; basal leaves sometimes persistent, not densely clustered; rays yellow

15. Cauline leaves at least at mid-stem sessile (± sessile) ..... A. latifolia

15' Cauline leaves at least at mid-stem petioled (petiole ± wide)

16. Leaves ± thick, often fleshy and ± red; heads 1(4), often nodding in bud; serpentine soils ..... A. cernua

16' Leaves ± thin, neither fleshy nor ± red; heads 1–5, not nodding in bud; not on serpentine

17. Proximal leaves generally toothed, ± strongly cordate (except stunted alpine plants); pappus short-barbed ..... A. cordifolia

17' Proximal leaves ± entire, base rounded (± cordate); pappus short-barbed to ± plumose ..... A. nevadensis

Contact/Feedback

Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.