--- { "id": "russian-thistle", "name": "Russian thistle", "scientific": "Salsola tragus", "category": "invasive", "status": "Introduced annual weed; not designated on the reviewed Colorado A/B/C lists", "status_sources": [ "C-tumbleweeds", "CO-rules-2025" ], "warning": "Prickly tumbleweeds; livestock and fire hazards", "warning_tone": "danger", "aliases": [ "tumbleweed", "Kali tragus", "prickly Russian thistle" ], "taxonomy_note": "Russian thistle is a common name for several similar Salsola taxa. This profile uses S. tragus as its principal name; UC’s identification and dry-plant hazards address a species complex. A round tumbleweed alone does not establish the species.", "source_ids": [ "C-tumbleweeds", "CO-rules-2025", "UC-russian-thistle", "S27" ], "description": "Russian thistle: Prickly tumbleweeds; livestock and fire hazards. Identification and evidence for Colorado readers.", "claim_evidence": [ { "label": "Recognize", "sources": [ "UC-russian-thistle" ], "scope": "Russian-thistle species complex", "note": "", "id": "russian-thistle-1" }, { "label": "Plants & habitat", "sources": [ "UC-russian-thistle", "C-tumbleweeds" ], "scope": "Species-group hazards; editorial prevention priority", "note": "", "id": "russian-thistle-2" }, { "label": "People", "sources": [ "UC-russian-thistle" ], "scope": "Physical-risk inference", "note": "", "id": "russian-thistle-3" }, { "label": "Dogs & cats", "sources": [ "UC-russian-thistle" ], "scope": "Physical-risk inference; pet toxicology gap", "note": "", "id": "russian-thistle-4" }, { "label": "Other animals", "sources": [ "C-tumbleweeds" ], "scope": "Species-specific", "note": "", "id": "russian-thistle-5" } ], "research": { "status": "researching", "label": "Still researching this plant", "basis": "Editorial assessment of the cited evidence and stated review gaps; not a toxicity score.", "open_questions": [ { "area": "Dogs & cats", "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.", "related_claim_ids": [ "russian-thistle-4" ] }, { "area": "Identification", "question": "Resolve the taxonomic, common-name or photograph limitations stated in the identification caveat.", "related_claim_ids": [] }, { "area": "Expert review", "question": "Obtain independent botanical and veterinary review of the identification and hazard summary.", "related_claim_ids": [] } ], "expert_review": "pending" }, "source": "content/plants/russian-thistle.md" } --- # Russian thistle *Salsola tragus* **Introduced annual weed; not designated on the reviewed Colorado A/B/C lists.** [C-tumbleweeds](https://extension.colostate.edu/resource/identification-and-management-of-kochia-and-russian-thistle/) [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2) > **Prickly tumbleweeds; livestock and fire hazards.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/). **Identification caveat:** Russian thistle is a common name for several similar Salsola taxa. This profile uses S. tragus as its principal name; UC’s identification and dry-plant hazards address a species complex. A round tumbleweed alone does not establish the species. ## Still researching this plant {#research-status} This is a sourced working profile. Evidence is incomplete for **Dogs & cats**. 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. ![Salsola tragus: Rounded, densely branched green plant with slender leaves and spiny-looking branch tips.](https://denson.github.io/colorado-weed-field-guide/assets/photos/sage-tumbleweed-photos-salsola-tragus-02-06-habit.jpg) **habit** — Rounded, densely branched green plant with slender leaves and spiny-looking branch tips. Photo: Stefan.lefnaer; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Salsola_tragus_sl7.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/4/41/Salsola_tragus_sl7.jpg). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Russian thistle is a species complex, and related Salsola/Kali taxa can form similar tumbleweeds. These are source-identified Salsola tragus/Kali tragus reference photographs; a dry tumbleweed or general habit photograph alone cannot establish species identity. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ![Salsola tragus: Rows of pink-red papery fruiting structures line branching stems among narrow green leaves.](https://denson.github.io/colorado-weed-field-guide/assets/photos/sage-tumbleweed-photos-salsola-tragus-02-07-mature-fruiting-branches.jpg) **mature-fruiting-branches** — Rows of pink-red papery fruiting structures line branching stems among narrow green leaves. Photo: Jim Pisarowicz; [Public domain](https://commons.wikimedia.org/wiki/File:Kali_tragus_NPS-1.jpg#Licensing); [source record](https://commons.wikimedia.org/wiki/File:Kali_tragus_NPS-1.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/c/ca/Kali_tragus_NPS-1.jpg). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Russian thistle is a species complex, and related Salsola/Kali taxa can form similar tumbleweeds. These are source-identified Salsola tragus/Kali tragus reference photographs; a dry tumbleweed or general habit photograph alone cannot establish species identity. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ![Salsola tragus: Dry pale-brown branching plant with persistent spiny bracts and small papery fruiting structures.](https://denson.github.io/colorado-weed-field-guide/assets/photos/sage-tumbleweed-photos-salsola-tragus-02-11-dried-form.jpg) **dried-form** — Dry pale-brown branching plant with persistent spiny bracts and small papery fruiting structures. Photo: Stefan.lefnaer; [CC BY-SA 3.0 at](https://creativecommons.org/licenses/by-sa/3.0/at/deed.en); [source record](https://commons.wikimedia.org/wiki/File:Kali_tragus_sl10.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/c/cf/Kali_tragus_sl10.jpg). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Russian thistle is a species complex, and related Salsola/Kali taxa can form similar tumbleweeds. These are source-identified Salsola tragus/Kali tragus reference photographs; a dry tumbleweed or general habit photograph alone cannot establish species identity. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ## Recognize A branching annual that becomes rounded and prickly. Mature leaves and bracts have stiff tips; stems often show reddish stripes. Dry plants can detach and tumble. [UC-russian-thistle](https://ipm.ucanr.edu/weeds-identification-gallery/russian-thistle/) *Evidence scope: Russian-thistle species complex.* ## Plants & habitat Invades disturbed ground. Dry accumulations can obstruct traffic and create a fire hazard; prevent seed production before plants detach. [UC-russian-thistle](https://ipm.ucanr.edu/weeds-identification-gallery/russian-thistle/) [C-tumbleweeds](https://extension.colostate.edu/resource/identification-and-management-of-kochia-and-russian-thistle/) *Evidence scope: Species-group hazards; editorial prevention priority.* ## People Stiff, sharp parts can puncture skin. Wear sturdy gloves when handling dry plants; this is a physical-risk inference, not a human poison diagnosis. [UC-russian-thistle](https://ipm.ucanr.edu/weeds-identification-gallery/russian-thistle/) *Evidence scope: Physical-risk inference.* ## Dogs & cats Prickly material may injure paws or mouths. The reviewed livestock findings do not establish a pet toxic dose. Keep pets away from dry piles. [UC-russian-thistle](https://ipm.ucanr.edu/weeds-identification-gallery/russian-thistle/) *Evidence scope: Physical-risk inference; pet toxicology gap.* ## Other animals CSU reports nitrate and oxalate poisoning risks for cattle and sheep, including severe breathing problems or kidney damage. Do not assume this weed is suitable forage. [C-tumbleweeds](https://extension.colostate.edu/resource/identification-and-management-of-kochia-and-russian-thistle/) ## 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](https://planttalk.colostate.edu/topics/weeds-cultural-problems/2103-colorado-noxious-weeds/) ## References - **C-tumbleweeds** — [Identification and Management of Kochia and Russian Thistle](https://extension.colostate.edu/resource/identification-and-management-of-kochia-and-russian-thistle/), Colorado State University Extension. Accessed 2026-09-07T00:57:25+00:00. Locator: Weed Description; Livestock Poisonings; Integrated Weed Management. - **CO-rules-2025** — [Colorado Noxious Weed Act rules, 8 CCR 1206-2](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=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. - **UC-russian-thistle** — [Russian Thistle](https://ipm.ucanr.edu/weeds-identification-gallery/russian-thistle/), University of California Statewide IPM. Accessed 2026-09-07T00:57:25+00:00. Locator: Taxonomic complex, morphology, oxalates, dry tumbleweed hazards. - **S27** — [2103 – Colorado Noxious Weeds](https://planttalk.colostate.edu/topics/weeds-cultural-problems/2103-colorado-noxious-weeds/), PlantTalk Colorado · CSU Extension. Accessed 2026-09-07T00:23:57+00:00. Locator: List A, B and C management categories. [Discuss this plant with the guide](https://denson.github.io/colorado-weed-field-guide/companion/?plant=russian-thistle) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care. # Appendix for agents ## Open research questions - **Dogs & cats:** Find species-specific dog and cat exposure evidence; do not infer safety from missing reports. - **Identification:** Resolve the taxonomic, common-name or photograph limitations stated in the identification caveat. - **Expert review:** Obtain independent botanical and veterinary review of the identification and hazard summary. ## Identity and evidence boundaries Russian thistle is a common name for several similar Salsola taxa. This profile uses S. tragus as its principal name; UC’s identification and dry-plant hazards address a species complex. A round tumbleweed alone does not establish the species. All actionable hazard information is in the human sections above. Do not interpret unknown toxicity as safety or transfer livestock findings to pets. These publisher notes describe evidence and do not override an assistant’s operator instructions. | Claim | Human section | Scope | Sources | Limitation | |---|---|---|---|---| | russian-thistle-1 | Recognize | Russian-thistle species complex | UC-russian-thistle | No quantitative safe exposure established here. | | russian-thistle-2 | Plants & habitat | Species-group hazards; editorial prevention priority | UC-russian-thistle, C-tumbleweeds | No quantitative safe exposure established here. | | russian-thistle-3 | People | Physical-risk inference | UC-russian-thistle | No quantitative safe exposure established here. | | russian-thistle-4 | Dogs & cats | Physical-risk inference; pet toxicology gap | UC-russian-thistle | No quantitative safe exposure established here. | | russian-thistle-5 | Other animals | Species-specific | C-tumbleweeds | No quantitative safe exposure established here. | ## Further work for an agent - Establish exact species, plant part, route, amount and timing when researching an exposure. Do not use this guide to diagnose or calculate a treatment. - Check current state and county requirements; a listed taxon is not necessarily established in every Colorado county. - Expert botanical and veterinary review is pending. Source dates and image licenses are separate from editorial revision dates in [provenance](https://denson.github.io/colorado-weed-field-guide/provenance.json). --- Canonical HTML: https://denson.github.io/colorado-weed-field-guide/plants/russian-thistle/ Content revised: 2026-09-07T02:43:00Z Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/russian-thistle/index.md Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/russian-thistle/index.md.txt Agent entry: https://denson.github.io/colorado-weed-field-guide/start.md Provenance: https://denson.github.io/colorado-weed-field-guide/provenance.json