---
{
  "id": "curlycup-gumweed",
  "name": "Curlycup gumweed",
  "scientific": "Grindelia squarrosa",
  "category": "native",
  "status": "Native Colorado plant · not on state Lists A/B/C",
  "status_sources": [
    "C-floristic-2020",
    "CO-rules-2025"
  ],
  "warning": "Sticky resin and conditional selenium concern",
  "warning_tone": "caution",
  "aliases": [
    "gumweed",
    "resinweed"
  ],
  "taxonomy_note": "Grindelia squarrosa includes multiple varieties. Photographs and this profile do not constitute a variety-level key or a selenium test.",
  "source_ids": [
    "C-floristic-2020",
    "CO-rules-2025",
    "F-grindelia",
    "S27"
  ],
  "description": "Curlycup gumweed: Sticky resin and conditional selenium concern. Identification and evidence for Colorado readers.",
  "claim_evidence": [
    {
      "label": "Identification",
      "sources": [
        "F-grindelia"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "curlycup-gumweed-1"
    },
    {
      "label": "People",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "curlycup-gumweed-2"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "F-grindelia"
      ],
      "scope": "Contact precaution inferred from livestock observations",
      "note": "",
      "id": "curlycup-gumweed-3"
    },
    {
      "label": "Other animals",
      "sources": [
        "F-grindelia"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "curlycup-gumweed-4"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "F-grindelia"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "curlycup-gumweed-5"
    },
    {
      "label": "Management & timing",
      "sources": [
        "F-grindelia",
        "S27"
      ],
      "scope": "Management synthesis",
      "note": "",
      "id": "curlycup-gumweed-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": "People",
        "question": "Clarify the human exposure effects and evidence limits described in this section.",
        "related_claim_ids": [
          "curlycup-gumweed-2"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "curlycup-gumweed-3"
        ]
      },
      {
        "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 56; Grindelia squarrosa",
    "basis": "Included in the 2020 statewide flora assessment. This is not a current county abundance survey.",
    "source_taxon": "Grindelia squarrosa"
  },
  "source": "content/plants/curlycup-gumweed.md"
}
---

# Curlycup gumweed

*Grindelia squarrosa*

**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)

> **Sticky resin and conditional selenium concern.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

**Identification caveat:** Grindelia squarrosa includes multiple varieties. Photographs and this profile do not constitute a variety-level key or a selenium test.

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

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

![Rounded, densely branching curlycup gumweed plant covered with yellow flower heads.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-range-photos-grindelia-squarrosa-habit-224643870.jpg)

**habit** — Rounded, densely branching curlycup gumweed plant covered with yellow flower heads.

Photo: Jesse Grove; [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0/); [source record](https://www.inaturalist.org/observations/131957641); [original image](https://inaturalist-open-data.s3.amazonaws.com/photos/224643870/original.jpg). Explicit iNaturalist observation taxon and Research Grade community identification; photograph visually reviewed for depicted features. This is source identification, not a new independent botanical determination. Source identifies this plant to species; no variety or subspecies determination is asserted. Downloaded iNaturalist large rendition; downloaded bytes retained unchanged. No local crop, retouching, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

![Side view of a yellow curlycup gumweed flower head with green, outward-curving bracts below it.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-range-photos-grindelia-squarrosa-flower-446344737.jpeg)

**flower** — Side view of a yellow curlycup gumweed flower head with green, outward-curving bracts below it.

Photo: Zach Earl; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); [source record](https://www.inaturalist.org/observations/249666100); [original image](https://inaturalist-open-data.s3.amazonaws.com/photos/446344737/original.jpeg). Explicit iNaturalist observation taxon and Research Grade community identification; photograph visually reviewed for depicted features. This is source identification, not a new independent botanical determination. Source identifies this plant to species; no variety or subspecies determination is asserted. Downloaded iNaturalist large rendition; downloaded bytes retained unchanged. No local crop, retouching, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.

![Curlycup gumweed buds with spreading green bracts beside toothed leaves on a reddish stem.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-range-photos-grindelia-squarrosa-buds-leaves-88114065.jpg)

**buds-leaves** — Curlycup gumweed buds with spreading green bracts beside toothed leaves on a reddish stem.

Photo: Jared Shorma; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); [source record](https://www.inaturalist.org/observations/55340556); [original image](https://inaturalist-open-data.s3.amazonaws.com/photos/88114065/original.jpg). Explicit iNaturalist observation taxon and Research Grade community identification; photograph visually reviewed for depicted features. This is source identification, not a new independent botanical determination. Source identifies this plant to species; no variety or subspecies determination is asserted. Downloaded iNaturalist large rendition; downloaded bytes retained unchanged. No local crop, retouching, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop.


## Identification

A branching, taprooted biennial or perennial with resinous foliage and flower heads. Growth form varies among the varieties grouped in this species. [F-grindelia](https://research.fs.usda.gov/feis/species-reviews/grisqu)

## 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

Sticky secretions are a practical grooming concern, inferred from reports of livestock coats becoming gummed. Pet ingestion toxicity is unresolved. [F-grindelia](https://research.fs.usda.gov/feis/species-reviews/grisqu)

*Evidence scope: Contact precaution inferred from livestock observations.*

## Other animals

Usually unpalatable to livestock. Resin can gum coats, and the plant can absorb selenium when it is available; this does not mean every specimen contains a toxic concentration. [F-grindelia](https://research.fs.usda.gov/feis/species-reviews/grisqu)

## Plants & habitat

It tolerates dry disturbed ground and may form dense patches on depleted range or roadsides. Native status and weediness depend on context. [F-grindelia](https://research.fs.usda.gov/feis/species-reviews/grisqu)

## Management & timing

Investigate site condition before broad removal. For an unwanted small patch, prevent seed production and monitor replacement vegetation. [F-grindelia](https://research.fs.usda.gov/feis/species-reviews/grisqu) [S27](https://planttalk.colostate.edu/topics/weeds-cultural-problems/2103-colorado-noxious-weeds/)

*Evidence scope: Management synthesis.*

## 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.
- **F-grindelia** — [Curlycup gumweed](https://research.fs.usda.gov/feis/species-reviews/grisqu), USDA Forest Service, Fire Effects Information System. Accessed 2026-09-07T02:24:48+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=curlycup-gumweed) — 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 56; Grindelia squarrosa. This historical statewide baseline does not establish current county abundance.

## Open research questions

- **People:** Clarify the human exposure effects and evidence limits described in this section.
- **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

Grindelia squarrosa includes multiple varieties. Photographs and this profile do not constitute a variety-level key or a selenium test.

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 |
|---|---|---|---|---|
| curlycup-gumweed-1 | Identification | Species-specific | F-grindelia | No quantitative safe exposure established here. |
| curlycup-gumweed-2 | People | Review limitation | Review limitation | No quantitative safe exposure established here. |
| curlycup-gumweed-3 | Dogs & cats | Contact precaution inferred from livestock observations | F-grindelia | No quantitative safe exposure established here. |
| curlycup-gumweed-4 | Other animals | Species-specific | F-grindelia | No quantitative safe exposure established here. |
| curlycup-gumweed-5 | Plants & habitat | Species-specific | F-grindelia | No quantitative safe exposure established here. |
| curlycup-gumweed-6 | Management & timing | Management synthesis | F-grindelia, S27 | 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/curlycup-gumweed/

Content revised: 2026-09-07T02:46:00Z

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

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/curlycup-gumweed/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