PlantKey Open ecological atlas
Planner
Home / Browse / Hieracium / Tall Hawkweed
Wikimedia Commons — CC, credited & licensed per image
Asteraceae family

Tall Hawkweed Hieracium piloselloides

Tall Hawkweed is an introduced perennial herb, found in Canada and the lower 48 states. It blooms May – Jul.

More about this plant

Hieracium piloselloides is a species of flowering plant in the family Asteraceae known by the common name tall hawkweed. It is native to Europe and it is present in North America as an introduced species and a common weed. Wikipedia →

⚠ Invasive here — plant a native instead USDA + GBIF

Tall Hawkweed 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.

Clasping Milkweed
Native ★
Clasping Milkweed
Asclepias amplexicaulis
●●●●●
Purple Milkweed
Native ★
Purple Milkweed
Asclepias purpurascens
●●●●●
Largeflower Tickseed
Native
Largeflower Tickseed
Coreopsis grandiflora
●●●●○
Greater Tickseed
Native
Greater Tickseed
Coreopsis major
●●●●○
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
Hardiness
≥ zone 5 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 · May – Jul — 32 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 ~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 1 bird · 1 mammal · 1 nectaring

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

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

Pinicola enucleator · Pine Grosbeak Ovis aries · Domestic Sheep

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 (16) 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)
[11] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[12] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[13] Wildlife & visitors — GloBI — Global Biotic Interactions (CC0)
[14] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[15] Caterpillar species — NHM HOSTS (CC0)
[16] 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).

Citation

Loading…

BibTeX 
Loading…