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Asteraceae family

European Hawkweed Hieracium lactucella

European Hawkweed is an introduced perennial herb, found in Canada and the lower 48 states.

More about this plant

Pilosella lactucella is a species of perennial plant from the family Asteraceae, found in Europe, New York and Nova Scotia (Canada). It is 9–20 centimetres (3.5–7.9 in) in height, with stems from 1–2 millimetres (0.039–0.079 in) wide. The leaves are spatula shaped and 5–8 centimetres (2.0–3.1 in) wide. The flowers bloom from May to July, the heads of which are 2–5 centimetres (0.79–1.97 in) tall. It was once described by Carl Linnaeus as Hieracium auricula and Pilosella auricula, but was recategorized by A. E. Roland and M. Zinck in 1998. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 7 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
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 ~4 caterpillar species

Hieracium supports ~4 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 modest genus.

Recorded feeding on Hieracium in North America, including:

Capperia ningoris · plume moth Cucullia florea · Gray Hooded-Owlet Dichomeris levisella · twirler moth Oxyptilus delawaricus · plume moth Papaipema eryngii · Rattlesnake-Master Borer Moth Xestia speciosa · owlet 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).
✦ Bees specialist-bee host

Specialist native bees depend on it.

Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Hieracium is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.

Xerces pollinator conservation →
Specialist hosts from Smith et al. 2024.
Wildlife & visitors 56 birds · 1 mammal · 1 nectaring

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

1 adult butterfly & moth species is recorded nectaring at its flowers:

Lycaena virgaureae · Scarce Copper
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 (1) Methods & honest limits
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).
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 (14) 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)
[07] Description — Wikipedia (CC BY-SA)
[08] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts · Smith et al. 2024 (CC BY)
[10] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[11] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[12] Wildlife & visitors — GloBI — Global Biotic Interactions (CC0)
[13] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[14] Caterpillar species — NHM HOSTS (CC0)
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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