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Asteraceae family

Sulphur Knapweed Centaurea sulphurea

Sulphur Knapweed is an introduced annual herb, found in the lower 48 states. It blooms Jun.

More about this plant

Centaurea sulphurea, the Sicilian star thistle or sulphur star knapweed, is an annual herb species in the family Asteraceae. It is native to southwestern Europe and it is known on other continents as an introduced species. It is one of the closest relatives to Centaurea solstitialis, an extremely invasive thistle in California, but Centaurea sulphurea has only established several populations in California since its introduction in the mid-19th century. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 11 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
Lifespan
Annual
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 · Jun — 11 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 ~3 caterpillar species

Centaurea supports ~3 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 Centaurea in North America, including:

Adaina montana · plume moth Agapeta zoegana · leafroller moth Apterona helix · bagworm moth Hemileuca eglanterina · Elegant Sheep Moth Megalographa biloba · owlet moth Metzneria paucipunctella · twirler moth
+ 4 more species →
Pelochrista medullana · leafroller moth Phyciodes mylitta · Mylitta Crescent Spodoptera praefica · Western Yellowstriped Armyworm Vanessa cardui · Painted Lady
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 (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
[10] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[12] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[13] Caterpillar species — NHM HOSTS (CC0)
[14] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
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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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