Greater Knapweed Centaurea scabiosa
Greater Knapweed is an introduced perennial herb, found in Canada and the lower 48 states. It grows to 2.2 ft.
More about this plant
Centaurea scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea. It is native to Europe and bears purple flower heads. Wikipedia →
Greater Knapweed 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.
Part of why it adapts so well: Greater Knapweed is a polyploid complex — multiple chromosome races are on record (2n = 20, 40). Spare genome copies give a plant extra raw material to evolve fast, and polyploidy is a documented correlate of successful plant invasions (te Beest et al. 2012). A labelled association from open cytology (ChromoDB), not a prediction for your specific site.
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Height
- 2.2 ft
- Lifespan
- Perennial
- Foliage
- Broadleaf
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:
✦ Bees 49 bee visitors
49 native & managed bee species are documented visiting Greater Knapweed — the 12 most-recorded:
Wildlife & visitors 61 nectaring
Open records of who else uses Greater Knapweed — a generalist food-web signal, kept separate from the keystone Ecological Value.
61 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
Related plants
More Centaurea →
How we know this (3) Methods & honest limits
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.
We place each species on Grime’s competitor–stress-tolerator–ruderal (C–S–R) triangle using the globally-calibrated “StrateFy” method: leaf size drives the competitor score, dense low-area leaves the stress-tolerator score, and thin high-area leaves the ruderal score. The result is a C/S/R percentage mix and one of 19 strategy classes; we show it in plain words and keep the percentages for the curious.
Honest limits: A species-mean strategy from pooled global leaf measurements — a broad ecological signal, not a precise per-plant or per-site value. Derived, never a measured 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.
Sources for this entry (23) Open & cited
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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