Spotted × diffuse knapweed hybrid

Discuss this plant with the guide — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

Centaurea × psammogena

Colorado noxious weed · List B — Stop the spread. CO-rules-2025

Established in some areas. Requirements vary by location: eradication, containment or suppression to stop further spread. This is a management category, separate from danger ratings. Category source · What the lists mean.

Hybrid identification needs expert review. Exposure help.

Identification caveat: The source explains chromosome and subspecies differences in the parents and uncertainty in older identifications. The photographs come from a community research-grade Colorado observation, not genetic testing. No parent-species poisoning syndrome is assumed for the hybrid.

Still researching this plant

This is a sourced working profile. Evidence is incomplete for People, Dogs & cats, Other animals. Identification and source-photo limits are explained below. Independent botanical and veterinary review is pending. Uncertainty is not a finding that the plant is safe.

Three views of this plant

Source-identified reference photographs; these are not a complete identification key. A source location outside Colorado does not establish local occurrence.

**head and bracts** — A pink-purple hybrid-knapweed head and several buds held beside branching stems; the source identifies this Littleton, Colorado plant as Centaurea × psammogena.
Tyler · CC0 1.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification is explicit; hybrid status has not been independently confirmed genetically.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

**habit** — A widely branched hybrid-knapweed plant with scattered pink-purple heads in dry vegetation; source location is Littleton, Colorado.
Tyler · CC0 1.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification is explicit; hybrid status has not been independently confirmed genetically.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

**flower** — Close view of a pale pink and purple hybrid-knapweed flower head; source location is Littleton, Colorado.
Tyler · CC0 1.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification is explicit; hybrid status has not been independently confirmed genetically.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

Recognize

A fertile hybrid of diffuse and spotted knapweed, often misidentified. A mix of parental appearance does not by itself prove hybrid identity. F-knapweed

Plants & habitat

The Forest Service records the hybrid in Colorado. Colorado lists the hybrid separately, so do not discard suspect plants from a weed survey simply because they do not fit a parent’s key. F-knapweed CO-rules-2025

People

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for people. Missing evidence does not establish safety.

Dogs & cats

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for dogs or cats. Missing evidence does not establish safety.

Other animals

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for livestock. Missing evidence does not establish safety.

Before taking action

Confirm identification and the requirements of your county weed program. For chemical treatment, follow the current product label, including restrictions around animals and water. S27

References

CO-rules-2025 — Colorado Noxious Weed Act rules, 8 CCR 1206-2, Colorado Secretary of State / Department of Agriculture. Accessed 2026-09-07T01:07:48+00:00. Locator: Parts 3.1, 4.1, 5.1; management provisions; effective May 15, 2025.
F-knapweed — Diffuse knapweed and hybrid taxonomy, USDA Forest Service Fire Effects Information System. Accessed 2026-09-07T01:21:11+00:00. Locator: Species identity, description, ecology and exposure evidence.
S27 — 2103 – Colorado Noxious Weeds, PlantTalk Colorado · CSU Extension. Accessed 2026-09-07T00:23:57+00:00. Locator: List A, B and C management categories.

Content revised 2026-09-07 03:50:00Z · Source checks dated separately in the references.