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Home / Browse / Epilobium / Glaucus Willowherb (subsp. fastigiatum)
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Pictured: Epilobium glaberrimum — the species. This subspecies isn’t separately illustrated.
Onagraceae family

Glaucus Willowherb (subsp. fastigiatum) Epilobium glaberrimum subsp. fastigiatum subspecies

Native

Glaucus Willowherb (subsp. fastigiatum) is a perennial wildflower native to Canada and the lower 48 states.

More about this plant

Epilobium glaberrimum is a species of willowherb known by the common name glaucous willowherb. This clumping perennial wildflower is native to western North America from central Canada to northern Mexico. It generally grows at some elevation in moist places. This plant is somewhat variable in appearance. It may exceed half a meter in height and has hairless foliage with leaves between one and 8 centimeters long. The flower has four notched petals in purple, pink, or white which may be only a couple of millimeters long to over a centimeter long each. The fruit is a narrow, sticklike capsule 2 to 7 centimeters long. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 6 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
Lifespan
Perennial
In the garden
Herb layer — Sits in the herb of a layered food forest or polyculture.Open guide →
derived roles
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 ~32 caterpillar species

Epilobium supports ~32 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 Epilobium in North America, including:

Acronicta oblinita · Smeared Dagger Moth Albuna pyramidalis · Fireweed Clearwing Moth Alypia langtoni · owlet moth Amphion floridensis · Nessus Sphinx Androloma maccullochii · Macculloch's Forester Anticlea multiferata · Many-Lined Carpet
+ 8 more species →
Dichomeris washingtoniella · twirler moth Ecliptopera silaceata · Small Phoenix Ecliptoptera silaceata · geometer (inchworm) moth Eudryas brevipennis · owlet moth Eudryas unio · Pearly Wood-Nymph Eulia ministrana · leafroller moth Eulithis destinata · geometer (inchworm) moth Eulithis diversilineata · Lesser Grapevine Looper Moth
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).
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.
Sources for this entry (12) 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
[06] Description — Wikipedia (CC BY-SA)
[07] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[08] Conservation rank — NatureServe Explorer (CC BY)
[09] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[10] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[11] Caterpillar species — NHM HOSTS (CC0)
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