--- { "id": "medusahead", "name": "Medusahead", "scientific": "Taeniatherum caput-medusae", "category": "invasive", "status": "Colorado noxious weed · List A — Eradicate", "status_sources": [ "CO-rules-2025" ], "warning": "Barbed awns; persistent fire-promoting thatch", "warning_tone": "danger", "aliases": [], "taxonomy_note": "Similar-looking native grasses exist. Awn and spike structure must be examined before identification or removal.", "source_ids": [ "CO-rules-2025", "WA-medusahead", "S27", "Fremont-list-definitions" ], "description": "Medusahead: Barbed awns; persistent fire-promoting thatch. Identification and evidence for Colorado readers.", "claim_evidence": [ { "label": "Recognize", "sources": [ "WA-medusahead" ], "scope": "Species-specific", "note": "", "id": "medusahead-1" }, { "label": "Plants & habitat", "sources": [ "WA-medusahead" ], "scope": "Species-specific", "note": "", "id": "medusahead-2" }, { "label": "People", "sources": [ "WA-medusahead" ], "scope": "Species-specific", "note": "", "id": "medusahead-3" }, { "label": "Dogs & cats", "sources": [ "WA-medusahead" ], "scope": "Species-specific", "note": "", "id": "medusahead-4" }, { "label": "Other animals", "sources": [ "WA-medusahead" ], "scope": "Species-specific", "note": "", "id": "medusahead-5" }, { "id": "medusahead-list-meaning", "label": "State-list meaning", "sources": [ "Fremont-list-definitions" ], "scope": "Colorado management-category definition; species classification retains its original status sources", "note": "Plain-language editorial label for a management category; not a toxicity or danger rating.", "reviewed": "2026-09-07" } ], "noxious_class": "A", "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": "Other animals", "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.", "related_claim_ids": [ "medusahead-5" ] }, { "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" }, "noxious_class_label": "A — Eradicate", "source": "content/plants/medusahead.md" } --- # Medusahead *Taeniatherum caput-medusae* **Colorado noxious weed · List A — Eradicate.** [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2) Uncommon in Colorado. All populations are designated for eradication statewide. This is a management category, separate from danger ratings. [Category source](https://fremontcountyco.gov/weed-control/weed-identification) · [What the lists mean](https://denson.github.io/colorado-weed-field-guide/safety/#weed-lists). > **Barbed awns; persistent fire-promoting thatch.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/). **Identification caveat:** Similar-looking native grasses exist. Awn and spike structure must be examined before identification or removal. ## Still researching this plant {#research-status} 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. ![Taeniatherum caput-medusae: Dense grass growth with numerous pale, spreading, long-awned heads.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-a-photos-taeniatherum-caput-medusae-1.jpg) **maturing heads** — Dense grass growth with numerous pale, spreading, long-awned heads. Photo: Matt Lavin from Bozeman, Montana, USA; [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0); [source record](https://commons.wikimedia.org/wiki/File:Taeniatherum_caput-medusae_(3872859565).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/e/e4/Taeniatherum_caput-medusae_%283872859565%29.jpg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Wikimedia server-resized derivative; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ![Taeniatherum caput-medusae: A broad straw-coloured stand beside a fence and building.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-a-photos-taeniatherum-caput-medusae-2.jpg) **infestation** — A broad straw-coloured stand beside a fence and building. Photo: Matt Lavin from Bozeman, Montana, USA; [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0); [source record](https://commons.wikimedia.org/wiki/File:Taeniatherum_caput-medusae_(3873644920).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/d/d2/Taeniatherum_caput-medusae_%283873644920%29.jpg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Wikimedia server-resized derivative; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ![Taeniatherum caput-medusae: Close view of green spikes with numerous long, slender awns.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-a-photos-taeniatherum-caput-medusae-3.jpg) **green heads** — Close view of green spikes with numerous long, slender awns. Photo: Matt Lavin from Bozeman, Montana, USA; [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0); [source record](https://commons.wikimedia.org/wiki/File:Taeniatherum_caput-medusae_(3873651200).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/3/3c/Taeniatherum_caput-medusae_%283873651200%29.jpg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Wikimedia server-resized derivative; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop. ## Recognize A winter annual grass with dense seed spikes and long, twisting, barbed awns. [WA-medusahead](https://www.nwcb.wa.gov/weeds/medusahead) ## Plants & habitat Competes strongly with native vegetation. Slowly decomposing, silica-rich thatch accumulates and can increase fire frequency. [WA-medusahead](https://www.nwcb.wa.gov/weeds/medusahead) ## People Barbed awns catch on clothing and can scratch; avoid bare-handed handling of mature seedheads. [WA-medusahead](https://www.nwcb.wa.gov/weeds/medusahead) ## Dogs & cats Awns pose a plausible physical injury concern, but this source is not a species-specific pet case series. Keep pets out of mature seedheads. [WA-medusahead](https://www.nwcb.wa.gov/weeds/medusahead) ## Other animals Poor forage quality and loss of desirable pasture are documented concerns. An unrestricted feeding-safety threshold is not established. [WA-medusahead](https://www.nwcb.wa.gov/weeds/medusahead) ## 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/) This is a statewide eradication priority. Contact your county weed program promptly for identification and an approved management and disposal plan. [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2) ## References - **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. - **WA-medusahead** — [Medusahead](https://www.nwcb.wa.gov/weeds/medusahead), Washington State Noxious Weed Control Board. Accessed 2026-09-07T01:09:00+00:00. Locator: Identification, ecological impacts, management; Washington legal class not applied to Colorado. - **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=medusahead) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care. # Appendix for agents ## Open research questions - **Other animals:** Clarify feeding and exposure risks for each animal group; do not transfer findings between species. - **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 Similar-looking native grasses exist. Awn and spike structure must be examined before identification or removal. 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 | |---|---|---|---|---| | medusahead-1 | Recognize | Species-specific | WA-medusahead | No quantitative safe exposure established here. | | medusahead-2 | Plants & habitat | Species-specific | WA-medusahead | No quantitative safe exposure established here. | | medusahead-3 | People | Species-specific | WA-medusahead | No quantitative safe exposure established here. | | medusahead-4 | Dogs & cats | Species-specific | WA-medusahead | No quantitative safe exposure established here. | | medusahead-5 | Other animals | Species-specific | WA-medusahead | 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). ## State-list label provenance The label “A — Eradicate” is this guide’s plain-language summary of [Fremont County’s Colorado noxious-weed definitions](https://fremontcountyco.gov/weed-control/weed-identification) [Fremont-list-definitions]. The letter and species assignment retain the status sources above. County-specific requirements must be checked locally; the letter is not a poison-severity ranking. --- Canonical HTML: https://denson.github.io/colorado-weed-field-guide/plants/medusahead/ Content revised: 2026-09-07T03:50:00Z Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/medusahead/index.md Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/medusahead/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