Purpledisk Sunflower Helianthus atrorubens
Purpledisk Sunflower is a perennial wildflower native to the lower 48 states. It blooms Aug – Oct. A host for pollen-specialist native bees.
More about this plant
Helianthus atrorubens is a North American species of sunflower known by the common name purpledisc sunflower. It is native to the southeastern United States. It is found in all the coastal states from Louisiana to Virginia, plus the inland states of Kentucky and Tennessee. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 7 derived from its U.S. range
- Lifespan
- Perennial
- 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 · 6 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.
6 native & managed bee species are documented visiting Purpledisk Sunflower :
Wildlife & visitors 1 nectaring
Open records of who else uses Purpledisk Sunflower — a generalist food-web signal, kept separate from the keystone Ecological Value.
1 adult butterfly & moth species is recorded nectaring at its flowers:
Across 41 U.S. vegetation-survey plots that recorded Purpledisk Sunflower, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.
Related plants
More Helianthus →
How we know this (2) Methods & honest limits
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 (21) 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).
Loading…
BibTeX
Loading…