Arnica discoidea (rayless arnica)

Plate 1 figs. a–h · 8 separate observations

Arnica discoidea, photographed by joergmlpts — fig. a joergmlpts, CC BY 4.0 / 2022-05-19 / obs. 198975005

Arnica discoidea, photographed by Arvel Hernandez — fig. b Arvel Hernandez, CC BY 4.0 / obs. 188661443

Arnica discoidea, photographed by George Williams — fig. c George Williams, CC BY 4.0 / obs. 138634562

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 4 botanical countries

Native distribution of Arnica discoidea, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows.

Region	TDWG code	Continent
California	CAL	NORTHERN AMERICA
Nevada	NEV
Oregon	ORE
Washington	WAS

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 326 in flower of 391 examined

20%

55%

89%

93%

85%

92%

Proportion of examined Arnica discoidea in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	0	too few examined
Feb	0	2	too few examined
Mar	3	15	20%	7% to 45%
Apr	22	40	55%	40% to 69%
May	114	128	89%	82% to 93%
Jun	122	131	93%	87% to 96%
Jul	52	61	85%	74% to 92%
Aug	11	12	92%	65% to 99%
Sep	2	2	too few examined
Oct	0	0	too few examined
Nov	0	0	too few examined
Dec	0	0	too few examined

Peak flowering in Jun. Each bar is the share of Arnica discoidea observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 326 of 391 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Also published as 13 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

Arnica alata Rydb.
Arnica cordifolia var. eradiata A.Gray
Arnica denudata var. eradiata (A.Gray) Cronquist
Arnica discoidea var. alata (Rydb.) Cronquist
Arnica discoidea var. discoidea
Arnica discoidea var. eradiata (A.Gray) Cronquist
Arnica falconaria Greene
Arnica grayi A.Heller
Arnica parviflora A.Gray
Arnica parviflora subsp. alata (Rydb.) Maguire
Arnica parviflora subsp. genuina Maguire
Arnica parviflora subsp. parviflora
Arnica sanhedrensis Rydb.

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.