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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

ARNICA

Steven J. Wolf & Theodore M. Barkley


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

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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].
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