---
{
  "id": "stinging-nettle",
  "name": "Stinging nettle",
  "scientific": "Urtica dioica",
  "category": "native",
  "status": "Native Colorado plant · not on state Lists A/B/C",
  "status_sources": [
    "C-floristic-2020",
    "CO-rules-2025"
  ],
  "warning": "Stinging hairs; this profile covers a taxonomic complex",
  "warning_tone": "caution",
  "aliases": [
    "Urtica gracilis",
    "Urtica dioica subsp. gracilis",
    "American stinging nettle"
  ],
  "taxonomy_note": "A broad, historical Urtica dioica treatment includes native American nettles (often now called Urtica gracilis) and introduced relatives. Colorado’s native status applies to the native elements; photos preserve their original identifications and do not prove every pictured subspecies occurs at your site.",
  "source_ids": [
    "C-floristic-2020",
    "CO-rules-2025",
    "N-urtica-dioica",
    "F-urtica",
    "S27"
  ],
  "description": "Stinging nettle: Stinging hairs; this profile covers a taxonomic complex. Identification and evidence for Colorado readers.",
  "claim_evidence": [
    {
      "label": "Identification",
      "sources": [
        "N-urtica-dioica",
        "F-urtica"
      ],
      "scope": "Broad Urtica dioica complex",
      "note": "",
      "id": "stinging-nettle-1"
    },
    {
      "label": "People",
      "sources": [
        "N-urtica-dioica"
      ],
      "scope": "Broad Urtica dioica complex",
      "note": "",
      "id": "stinging-nettle-2"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "N-urtica-dioica"
      ],
      "scope": "Precautionary inference; pet evidence unresolved",
      "note": "",
      "id": "stinging-nettle-3"
    },
    {
      "label": "Other animals",
      "sources": [
        "F-urtica"
      ],
      "scope": "Broad-complex forage evidence",
      "note": "",
      "id": "stinging-nettle-4"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "F-urtica",
        "N-urtica-dioica"
      ],
      "scope": "Broad Urtica dioica complex",
      "note": "",
      "id": "stinging-nettle-5"
    },
    {
      "label": "Management & timing",
      "sources": [
        "F-urtica"
      ],
      "scope": "Broad-complex management",
      "note": "",
      "id": "stinging-nettle-6"
    }
  ],
  "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": [
          "stinging-nettle-3"
        ]
      },
      {
        "area": "Other animals",
        "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.",
        "related_claim_ids": [
          "stinging-nettle-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"
  },
  "colorado_relevance": {
    "source_id": "C-floristic-2020",
    "locator": "Appendix B; PDF page 84; Urtica dioica",
    "basis": "Included in the 2020 statewide flora assessment. This is not a current county abundance survey.",
    "source_taxon": "Urtica dioica"
  },
  "source": "content/plants/stinging-nettle.md"
}
---

# Stinging nettle

*Urtica dioica*

**Native Colorado plant · not on state Lists A/B/C.** [C-floristic-2020](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf) [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2)

> **Stinging hairs; this profile covers a taxonomic complex.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

**Identification caveat:** A broad, historical Urtica dioica treatment includes native American nettles (often now called Urtica gracilis) and introduced relatives. Colorado’s native status applies to the native elements; photos preserve their original identifications and do not prove every pictured subspecies occurs at your site.

## Still researching this plant {#research-status}

This is a sourced working profile. Evidence is incomplete for **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.

![Urtica dioica: An upright nettle stem bearing toothed opposite leaves and slender branching flower clusters.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-hazard-photos-urtica-dioica-1.jpg)

**flowering habit** — An upright nettle stem bearing toothed opposite leaves and slender branching flower clusters.

Photo: Przykuta; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Urtica_dioica_pokr%C3%B3j2_23.06.2012_p.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/8/84/Urtica_dioica_pokr%C3%B3j2_23.06.2012_p.jpg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference, not an independent specimen-based taxonomic determination. This guide uses the explicitly requested broad Urtica dioica treatment. Photo 10-01 is source-labelled Urtica dioica. Photos 10-02 and 10-03 are source-labelled Urtica gracilis gracilis (subspecies rank), a native North American nettle also treated historically as Urtica dioica subsp. gracilis. Those narrow source identifications are preserved and are not asserted to be Eurasian U. dioica sensu stricto. Wikimedia server-resized derivative; no local crop, colour change or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

![Urtica dioica: A long leafy branch with sharply toothed leaves and small hanging reproductive clusters; the source identifies Urtica gracilis gracilis.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-hazard-photos-urtica-dioica-2.jpg)

**native nettle foliage** — A long leafy branch with sharply toothed leaves and small hanging reproductive clusters; the source identifies Urtica gracilis gracilis.

Photo: John A Haskins; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); [source record](https://www.inaturalist.org/observations/175285117); [original image](https://inaturalist-open-data.s3.amazonaws.com/photos/304622103/original.jpeg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference, not an independent specimen-based taxonomic determination. This guide uses the explicitly requested broad Urtica dioica treatment. Photo 10-01 is source-labelled Urtica dioica. Photos 10-02 and 10-03 are source-labelled Urtica gracilis gracilis (subspecies rank), a native North American nettle also treated historically as Urtica dioica subsp. gracilis. Those narrow source identifications are preserved and are not asserted to be Eurasian U. dioica sensu stricto. iNaturalist large server-resized photo; no local crop, colour change or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

![Urtica dioica: A detached compact reproductive cluster photographed on a pale surface; the source identifies Urtica gracilis gracilis.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-hazard-photos-urtica-dioica-3.jpg)

**native nettle reproductive cluster** — A detached compact reproductive cluster photographed on a pale surface; the source identifies Urtica gracilis gracilis.

Photo: John A Haskins; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); [source record](https://www.inaturalist.org/observations/175285117); [original image](https://inaturalist-open-data.s3.amazonaws.com/photos/304614058/original.jpeg). Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference, not an independent specimen-based taxonomic determination. This guide uses the explicitly requested broad Urtica dioica treatment. Photo 10-01 is source-labelled Urtica dioica. Photos 10-02 and 10-03 are source-labelled Urtica gracilis gracilis (subspecies rank), a native North American nettle also treated historically as Urtica dioica subsp. gracilis. Those narrow source identifications are preserved and are not asserted to be Eurasian U. dioica sensu stricto. iNaturalist large server-resized photo; no local crop, colour change or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.


## Identification

A rhizomatous perennial with opposite, toothed leaves, small greenish flower clusters and stinging hairs. It often forms dense patches in moist, fertile ground. [N-urtica-dioica](https://plants.ces.ncsu.edu/plants/urtica-dioica/) [F-urtica](https://research.fs.usda.gov/feis/species-reviews/urtdio)

*Evidence scope: Broad Urtica dioica complex.*

## People

Contact with stinging hairs can cause burning and itching. Avoid testing identification by touching the plant. [N-urtica-dioica](https://plants.ces.ncsu.edu/plants/urtica-dioica/)

*Evidence scope: Broad Urtica dioica complex.*

## Dogs & cats

Keep faces and exposed skin away from stinging vegetation. This is a contact precaution based on the plant’s hairs; the reviewed sources do not establish pet-specific ingestion effects or a safe exposure. [N-urtica-dioica](https://plants.ces.ncsu.edu/plants/urtica-dioica/)

*Evidence scope: Precautionary inference; pet evidence unresolved.*

## Other animals

Fresh nettles are generally unpalatable to livestock. Reports of processed nettle forage do not establish that standing plants or home preparations are safe for every animal. [F-urtica](https://research.fs.usda.gov/feis/species-reviews/urtdio)

*Evidence scope: Broad-complex forage evidence.*

## Plants & habitat

Patches can crowd a small garden yet provide cover and support insects in suitable habitat. Soil disturbance can redistribute rhizomes. [F-urtica](https://research.fs.usda.gov/feis/species-reviews/urtdio) [N-urtica-dioica](https://plants.ces.ncsu.edu/plants/urtica-dioica/)

*Evidence scope: Broad Urtica dioica complex.*

## Management & timing

Where removal is necessary, protect against contact and plan follow-up for rhizome regrowth. Mowing can produce new shoots rather than eliminate the patch. [F-urtica](https://research.fs.usda.gov/feis/species-reviews/urtdio)

*Evidence scope: Broad-complex management.*

## 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-floristic-2020** — [Colorado Floristic Quality Assessment: 2020 Update](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf), Colorado Natural Heritage Program, Colorado State University. Accessed 2026-09-07T02:27:33+00:00. Locator: Appendix B, Colorado species list: scientific name and native/non-native fields.
- **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.
- **N-urtica-dioica** — [Urtica dioica](https://plants.ces.ncsu.edu/plants/urtica-dioica/), NC State Extension. Accessed 2026-09-07T02:23:13+00:00. Locator: Description, identification attributes and plant problems; toxicity section where present.
- **F-urtica** — [Stinging nettle](https://research.fs.usda.gov/feis/species-reviews/urtdio), USDA Forest Service, Fire Effects Information System. Accessed 2026-09-07T02:24:50+00:00. Locator: Taxonomy, distribution, botanical description, wildlife/livestock values and management.
- **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=stinging-nettle) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

# Appendix for agents

Colorado inclusion: [C-floristic-2020](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf), Appendix B; PDF page 84; Urtica dioica. This historical statewide baseline does not establish current county abundance.

## Open research questions

- **Dogs & cats:** Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.
- **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

A broad, historical Urtica dioica treatment includes native American nettles (often now called Urtica gracilis) and introduced relatives. Colorado’s native status applies to the native elements; photos preserve their original identifications and do not prove every pictured subspecies occurs at your site.

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 |
|---|---|---|---|---|
| stinging-nettle-1 | Identification | Broad Urtica dioica complex | N-urtica-dioica, F-urtica | No quantitative safe exposure established here. |
| stinging-nettle-2 | People | Broad Urtica dioica complex | N-urtica-dioica | No quantitative safe exposure established here. |
| stinging-nettle-3 | Dogs & cats | Precautionary inference; pet evidence unresolved | N-urtica-dioica | No quantitative safe exposure established here. |
| stinging-nettle-4 | Other animals | Broad-complex forage evidence | F-urtica | No quantitative safe exposure established here. |
| stinging-nettle-5 | Plants & habitat | Broad Urtica dioica complex | F-urtica, N-urtica-dioica | No quantitative safe exposure established here. |
| stinging-nettle-6 | Management & timing | Broad-complex management | F-urtica | 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/stinging-nettle/

Content revised: 2026-09-07T02:43:00Z

Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/stinging-nettle/index.md

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/stinging-nettle/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