

Broadleaf Arnica Arnica latifolia
Broadleaf Arnica is a perennial wildflower native to Alaska, Canada, and the lower 48 states. It grows to 2 ft and blooms Jun in full sun – part shade, with brown fruit.
More about this plant
Arnica latifolia is a species of arnica in the sunflower family, known by the common names broadleaf arnica, broad leaved arnica, mountain arnica, and daffodil leopardbane. It is native to western North America from Alaska east to Northwest Territories and south to Mono County, California, and Taos County, New Mexico. It grows in mountain habitat such as forest and meadows. Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Full sun – part shade
- Soil & moisture
- High moisture
- Soil pH
- 6–7.2
- Fertility need
- Medium
- Adapts to
- Coarse (sandy), Medium (loam)
- Hardiness
- USDA zone 4+
- Height
- 2 ft
- Spacing
- 2–2.5 ft apart from USDA planting density
- Spread
- None — clumping
- Growth rate
- Moderate
- Growth form
- Single crown
- Lifespan
- Perennial · moderate
- Foliage
- Broadleaf · medium texture
- Active growth
- Spring & summer
- Fruit
- Brown
- Flower colour
- Yellow AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed, Container, Sprigs
- Seed starting
- No stratification needed
- Seeds ripen
- Summer seed-collection / harvest window
- In the trade
- Contract growing only
- Deer browsing
- Low often deer-resistant
- Resprouts if cut
- No
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Arnica in North America, including:
✦ Bees 3 bee visitors
3 native & managed bee species are documented visiting Broadleaf Arnica :
Wildlife & visitors 5 nectaring
Open records of who else uses Broadleaf Arnica — a generalist food-web signal, kept separate from the keystone Ecological Value.
5 adult butterfly & moth species are recorded nectaring at its flowers:
Across 253 U.S. vegetation-survey plots that recorded Broadleaf Arnica, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.
How we know this (3) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (34) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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