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iNaturalist — CC, credited & licensed per image
Dennstaedtiaceae family

Western Brackenfern Pteridium aquilinum

Native
Deer-resistant — Low palatability to browsing deer. Usually passed over, but no plant is truly deer-proof when food is scarce.
USDA livestock toxicity rating — not a pet assessment. See the Toxicity detail further down for what's documented.
Also known as: Bracken · bracken fern

Western Brackenfern is a perennial fern native to Alaska, Canada, and Hawaii. It grows to 6.6 ft in full sun.

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
USDA PLANTS — Sun · Soil & moisture
USDA — SoilPH — Soil pH
USDA PLANTS (DwCA, Zenodo 17903503) — Fertility Requirement / Soil Adaptation — Fertility need · Adapts to
USDA — Temp-Min °F — Hardiness
Sun
Full sun
Soil & moisture
Medium moisture
Soil pH
4.5–7
Fertility need
Low
Adapts to
Coarse (sandy), Medium (loam)
Hardiness
USDA zone 3+
Size & form
Sources · Size & form
USDA PLANTS (DwCA, Zenodo 17903503) — Height, Mature — Height
USDA PLANTS (DwCA, Zenodo 17903503) — Planting Density (per acre) — Spacing
USDA PLANTS (DwCA, Zenodo 17903503) — Growth Rate / Spread / Growth Form / Lifespan / Active Growth Period / Seed Period — Spread · Growth rate · Growth form · Active growth
USDA PLANTS — Lifespan
TRY Plant Trait Database (CC BY 4.0) · USDA PLANTS — Foliage
USDA PLANTS (DwCA, Zenodo 17903503) — Fruit/Seed Color / Fruit Persistence — Fruit
Height
6.6 ft
Spacing
2–4 ft apart from USDA planting density
Spread
Moderate
Growth rate
Moderate
Growth form
Rhizomatous
Lifespan
Perennial · moderate
Foliage
Broadleaf · medium texture
Active growth
Spring & summer
Fruit
Brown
In the garden
Sources · In the garden
USDA PLANTS (DwCA, Zenodo 17903503) — Propagation Method / Commercial Availability — Propagate by · In the trade
USDA PLANTS (DwCA, Zenodo 17903503) — Germination (cold stratification) — Seed starting
USDA PLANTS — Seed Period — Seeds ripen
USDA PLANTS (DwCA, Zenodo 17903503) — Foliage Texture / Browse Palatability / Resprout — Deer browsing · Resprouts if cut
Propagate by
Seed, Bare root, Sprigs, Bulbs
Seed starting
No stratification needed
Seeds ripen
Summer – Autumn seed-collection / harvest window
In the trade
Routinely available
Deer browsing
Low often deer-resistant
Resprouts if cut
No
Shrub layer — Sits in the shrub of a layered food forest or polyculture.Open guide →
Chop-and-drop biomass — Soft, low-density wood is quick-growing and easy to cut back — coppice it and drop the trimmings in place as mulch.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 — USDA PLANTS (DwCA, Zenodo 17903503) — BloomPeriod
When to sow · for your area

Sow timing keys off your local last- and first-frost dates.

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

Pteridium 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 Pteridium in North America, including:

Arctia caja · Garden Tiger ✦ Callopistria cordata · Silver-Spotted Fern Moth ✦ Callopistria mollissima · Pink-Shaded Fern Moth ✦ Eueretagrotis perattentus · Two-Spot Dart Moth ✦ Euplexia benesimilis · American Angle Shades ✦ Homochlodes fritillaria · Pale Homochlodes ✦
+ 8 more species →
Homochlodes lactispargaria · geometer (inchworm) moth ✦ Leptarctia californiae · tiger moth ✦ Melanchra adjuncta · Hitched Arches ✦ Melanchra assimilis · Black Arches ✦ Olethreutes osmundana · leafroller moth ✦ Papaipema pterisii · Bracken Borer Moth ✦ Paradiarsia littoralis · owlet moth ✦ Peridroma saucia · Pearly Underwing ✦
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). ✦ = recorded on this exact species.
✦ Bees 8 bee visitors
Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI →
Wildlife & visitors 1 mammal · 5 nectaring

Open records of who else uses Western Brackenfern — a generalist food-web signal, kept separate from the keystone Ecological Value.

Recorded eaten by 1 mammal species (fruit, seed, browse):

Odocoileus hemionus · Mule Deer

5 adult butterfly & moth species are recorded nectaring at its flowers:

Pararge aegeria · Speckled Wood Coenonympha arcania · Pearly Heath Argynnis paphia · Silver-Washed Fritillary Polygonia c-album · Comma Ceramica pisi
Interaction records (observations, not exhaustive) from GloBI → (CC0). Counts are distinct species; names are the most-recorded. Common names from Wikidata (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.
Frequently grows with

Across 738 U.S. vegetation-survey plots that recorded Western Brackenfern, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.

Cat Greenbrier · 42% Longleaf Pine · 40% Red Maple · 39% Blackgum · 38% Narrowleaf Silkgrass · 33% Common Persimmon · 32% Dwarf Huckleberry · 32% Inkberry · 28%
By region — what it grows with near you
"%" = 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 (3) Methods & honest limits
Leaf build Direct fact

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.

Díaz, S. et al. (2022) The global spectrum of plant form and function: enhanced species-level trait dataset. Scientific Data 9:755.
Photosynthesis Direct fact

A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.

Kattge, J. et al. TRY plant trait database — Categorical Traits Dataset (2012).
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 (38) 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)
[18] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[19] Wetland indicator — USACE National Wetland Plant List (2022)
[21] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[22] Conservation rank — NatureServe Explorer (CC BY)
[24] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[25] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[26] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[27] Wildlife & visitors — GloBI — Global Biotic Interactions (CC0)
[28] Rooting depth — Fan et al. 2017 (Dryad, CC0)
[32] Other common names — Wikidata (CC0)
[34] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[35] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[36] Caterpillar species — NHM HOSTS (CC0)
[37] 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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