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Aquifoliaceae family

English Holly Ilex aquifolium

Also known as: holly

English Holly is an introduced perennial tree, found in Canada, Hawaii, and the lower 48 states. It grows to 21 ft and blooms May – Jun.

More about this plant

Ilex aquifolium, the holly, common holly, English holly, European holly, or occasionally Christmas holly, is a species of flowering plant in the family Aquifoliaceae, native to western and southern Europe, northwest Africa, and southwest Asia. It is regarded as the type species of the genus Ilex, which by association is also called holly. It is an evergreen tree or shrub found, for example, in shady areas of forests of oak and in beech hedges. In the British Isles it is one of very few native hardwood evergreen trees. It has a great capacity to adapt to different conditions and is a pioneer species that repopulates the margins of forests or clearcuts. Wikipedia →

⚠ Invasive here — plant a native instead USDA + GBIF

English Holly is flagged invasive in the U.S. These natives fill a similar niche — same growth habit, bloom season, height, and region — so you keep the look and feed local wildlife instead of spreading a problem.

Matched on growth habit · bloom months · mature height · shared U.S. range (USDA + GBIF) — a starting point, not a prescription.

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Niinemets & Valladares 2006 (CC0) — Drought tolerance · Shade tolerance · Wet-soil tolerance
Hardiness
≥ zone 8 derived from its U.S. range
Drought tolerance
Moderate
Shade tolerance
High
Wet-soil tolerance
Low waterlogging
Size & form
Sources · Size & form
TRY Plant Trait Database (CC BY 4.0) — Height · Foliage
USDA PLANTS — Lifespan
Height
21 ft
Lifespan
Perennial
Foliage
Evergreen broadleaf
In the garden
Sub-canopy / understory layer — Sits in the understory 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 · May – Jun — 28 obs · USA-NPN — Nature's Notebook (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 ~39 caterpillar species

Ilex supports ~39 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.

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 · 30 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. Ilex is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.

Specialist hosts from Smith et al. 2024. Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI →
Wildlife & visitors 6 birds · 5 nectaring

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

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.
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 (27) 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 — US-RIIS v2.0 (USGS)
[06] Wetland indicator — USACE National Wetland Plant List (2022)
[08] Description — Wikipedia (CC BY-SA)
[09] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts · Smith et al. 2024 (CC BY)
[11] Conservation rank — NatureServe Explorer (CC BY)
[14] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[15] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[16] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[17] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[18] Wildlife & visitors — GloBI — Global Biotic Interactions (CC0)
[21] Other common names — Wikidata (CC0)
[22] Stress tolerance — Niinemets & Valladares 2006 (CC0)
[24] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[25] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[26] Caterpillar species — NHM HOSTS (CC0)
[27] 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.
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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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