Taurian thistle
Discuss this plant with the guide — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.
Onopordum tauricum
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.
Sharp spines; taxon listed as Scotch thistle. Exposure help.
Identification caveat: Onopordum acanthium has its own profile. Identification can be difficult; the reference study documents morphological variation among Italian populations, not Colorado impact severity.
Still researching this plant
This is a sourced working profile. Evidence is incomplete for 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.
Louis Aureglia · CC BY 4.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification and visible consistency checked; not an independent specimen determination.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Louis Aureglia · CC BY 4.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification and visible consistency checked; not an independent specimen determination.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Louis Aureglia · CC BY 4.0
Photo source and identification
Original record · Original image
Explicit research-grade community taxon identification; visually inspected Community identification and visible consistency checked; not an independent specimen determination.
iNaturalist large-size rendering; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Recognize
Tall, spiny, winged stems and glandular hairs; often greener and less woolly than O. acanthium. P-tauricum
Plants & habitat
Colorado lists O. tauricum as a separate List B entry under the common name Scotch thistle. Confirm the species with your county program. CO-rules-2025
Evidence scope: Regulatory status.
People
Spiny stems and leaves warrant protective handling. P-tauricum
Evidence scope: Physical-risk inference.
Dogs & cats
Spines may injure paws or mouths. No pet-specific chemical toxicity is established here. P-tauricum
Evidence scope: Physical-risk inference.
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.
- P-tauricum — Morphological and Genomic Differences in the Italian Populations of Onopordum tauricum, Plants journal / authors; archived by US National Library of Medicine. Accessed 2026-09-07T01:18:57+00:00. Locator: Species or hybrid identity, description and ecology.
- 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.