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Asteraceae family

Threenerve Fleabane Erigeron subtrinervis

Native Specialist-bee host

Threenerve Fleabane is a perennial wildflower native to the lower 48 states. It blooms Jul – Aug. A host for pollen-specialist native bees.

More about this plant

Erigeron subtrinervis, called the three-nerved daisy, the three-nerve fleabane, or the hairy showy daisy, is a North American species of flowering plants in the family Asteraceae. It grows in various mountains of western Canada and the western United States: Rocky Mountains, northern Cascades, Black Hills, etc., from British Columbia and Washington state east to North Dakota and south as far as New Mexico. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 4 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
TRY Plant Trait Database (CC BY 4.0) — Foliage
Lifespan
Perennial
Foliage
Broadleaf
In the garden
Herb layer — Sits in the herb of a layered food forest or polyculture.Open guide →
derived roles
The garden year bloom → fruit → fall colour
J
F
M
A
M
J
J
A
S
O
N
D
Bloom
Bloom (the flower's colour)
Bloom · Jul – Aug — 647 obs · Herbarium specimens — Park et al. 2023 (CC BY 4.0)
Species characteristics from USDA PLANTS (public domain) + TRY (CC BY) — general guidance, not a guarantee for your exact site. Deer "browsing" is documented palatability, not a deer-proof claim.

Wildlife & pollinators

How pollinator value is scored →
❧ Caterpillar hosts ~15 caterpillar species

Erigeron supports ~15 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 moderate genus.

Recorded feeding on Erigeron in North America, including:

Agonopterix arnicella · concealer moth Archips purpurana · leafroller moth Argyrotaenia franciscana · Orange Tortrix Bucculatrix angustata · ribbed cocoon-maker moth Caloreas augustella Charidryas damoetas · brush-footed butterfly
+ 8 more species →
Charidryas palla · brush-footed butterfly Cucullia florea · Gray Hooded-Owlet Cucullia lilacina · owlet moth Cucullia speyeri · owlet moth Dichomeris stipendiaria · twirler moth Grammia williamsii · Williams' Tiger Moth Herpetogramma pertextalis · Bold-Feathered Grass Moth Hyles lineata · White-Lined Sphinx
Keystone count (genus-level) from Warren II 2026 (CC0) · Tallamy host-use records. Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0).
✦ Bees specialist-bee host · 26 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. Erigeron is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.

Xerces pollinator conservation →

26 native & managed bee species are documented visiting Threenerve Fleabane — the 12 most-recorded:

Ceratina nanula · Dwarf Ceratina Heriades cressoni Bombus bifarius · Two Form Bumble Bee Lasioglossum knereri · sweat bee Bombus mixtus · Fuzzy-Horned Bumble Bee Hoplitis grinnelli
+ 6 more bees →
Halictus confusus · sweat bee Halictus tripartitus · sweat bee Heriades carinata Halictus rubicundus · sweat bee Lasioglossum pruinosum · sweat bee Megachile subnigra · leafcutter bee · ✦ specialist
Specialist hosts from Smith et al. 2024. Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI → · ✦ = pollen-specialist bee (Smith et al. 2024)
Species thumbnails re-hosted from iNaturalist — Creative Commons, credited per image (hover for credit). Click any species to see it on iNaturalist. Not exhaustive; many taxa have no openly-licensed photo yet.
Frequently grows with

Across 25 U.S. vegetation-survey plots that recorded Threenerve Fleabane, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.

Common Yarrow · 84% Bluebell Bellflower · 68% Idaho Fescue · 68% Northern Bedstraw · 64% Kentucky Bluegrass · 60% Missouri Goldenrod · 60% Small-leaf Pussytoes · 56% Timber Oatgrass · 52%
"%" = share of this plant's plots that also held the species. From sPlotOpen → (Sabatini et al. 2021, CC BY 4.0) — open vegetation plots: wild community composition, not garden design.
How we know this (1) Methods & honest limits
Climate niche (heat tolerance & native rainfall) Derived

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.

Realized-niche / climate-envelope approach (Pearson & Dawson 2003; Soberón 2007). Climate: NOAA NCEI nClimDiv county normals (1991–2020).
Derived values are computed from open data by a published method — labelled, cited, and never shown as a direct observation. Full methodology →
Sources for this entry (22) Open & cited
[01] Scientific name & family — USDA PLANTS (DwCA, Zenodo 17903503)
[02] Growth habit & duration — USDA PLANTS (DwCA, Zenodo 17903503)
[03] Native status & distribution — USDA PLANTS (DwCA, Zenodo 17903503)
[04] Common name — USDA PLANTS (via GBIF)
[05] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[07] Description — Wikipedia (CC BY-SA)
[08] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts · Smith et al. 2024 (CC BY)
[10] Conservation rank — NatureServe Explorer (CC BY)
[12] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[13] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[14] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[17] Bee specialists — Smith et al. 2024 (Zenodo, CC BY 4.0)
[18] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[19] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[20] Caterpillar species — NHM HOSTS (CC0)
[21] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
Spot an error or have a better photo? Every field links to its source, and the whole dataset is open.
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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