Stiff Sunflower Helianthus pauciflorus
Stiff Sunflower is a perennial wildflower native to Canada and the lower 48 states. It grows to 1.5 ft and blooms Jul – Aug. A host for pollen-specialist native bees.
More about this plant
Helianthus pauciflorus, called the stiff sunflower, is a North American plant species in the family Asteraceae. It is widespread across the Great Plains, the Rocky Mountains, and the Great Lakes region, and naturalized in scattered locations in the eastern United States and in much of southern Canada. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Height
- 1.5 ft
- Lifespan
- Perennial
- Foliage
- Broadleaf
- Flower colour
- Yellow AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~75 caterpillar species
Helianthus supports ~75 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a strong genus.
Recorded feeding on Helianthus in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees specialist-bee host · 113 bee visitors
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Helianthus is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
113 native & managed bee species are documented visiting Stiff Sunflower — the 12 most-recorded:
Related plants
More Helianthus →
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 (23) 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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