---
{
  "id": "leafy-spurge",
  "name": "Leafy spurge",
  "scientific": "Euphorbia esula",
  "category": "invasive",
  "status": "Colorado noxious weed · List B — Stop the spread",
  "status_sources": [
    "J-leafy-spurge"
  ],
  "warning": "Irritating sap; eye injury risk",
  "warning_tone": "danger",
  "aliases": [],
  "taxonomy_note": "Colorado references use Euphorbia esula. Leafy-spurge taxonomy can involve closely related taxa; this profile does not resolve every population or hybrid.",
  "source_ids": [
    "J-leafy-spurge",
    "N-euphorbia-esula",
    "Fremont-list-definitions"
  ],
  "description": "Leafy spurge: Irritating sap; eye injury risk. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "N-euphorbia-esula"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "leafy-spurge-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "J-leafy-spurge"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "leafy-spurge-2"
    },
    {
      "label": "People",
      "sources": [
        "N-euphorbia-esula"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "leafy-spurge-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "N-euphorbia-esula"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "leafy-spurge-4"
    },
    {
      "label": "Other animals",
      "sources": [
        "J-leafy-spurge"
      ],
      "scope": "Animal-group-specific management evidence",
      "note": "",
      "id": "leafy-spurge-5"
    },
    {
      "id": "leafy-spurge-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": "B",
  "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": "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": "B — Stop the spread",
  "source": "content/plants/leafy-spurge.md"
}
---

# Leafy spurge

*Euphorbia esula*

**Colorado noxious weed · List B — Stop the spread.** [J-leafy-spurge](https://www.jeffco.us/2406/Leafy-Spurge)

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](https://fremontcountyco.gov/weed-control/weed-identification) · [What the lists mean](https://denson.github.io/colorado-weed-field-guide/safety/#weed-lists).

> **Irritating sap; eye injury risk.** Native status, garden use and noxious-weed class are separate from toxicity. [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

**Identification caveat:** Colorado references use Euphorbia esula. Leafy-spurge taxonomy can involve closely related taxa; this profile does not resolve every population or hybrid.

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

This is a sourced working profile. The cited findings are available below. 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

Photos are source-identified examples, not a complete identification key. Check leaves, stems, flowers and fruit together. Locations are not assumed to be in Colorado.

![Euphorbia esula: Dense upright leafy stems topped with yellow-green flower clusters.](https://denson.github.io/colorado-weed-field-guide/assets/photos/invasive-euphorbia-esula-habit.jpg)

**habit** — Dense upright leafy stems topped with yellow-green flower clusters.

Photo: H. Zell; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Euphorbia_esula_001.JPG); [original image](https://upload.wikimedia.org/wikipedia/commons/8/81/Euphorbia_esula_001.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.  Leafy-spurge taxonomy is complex. North American invasive leafy spurge is frequently assigned to Euphorbia virgata or an E. esula aggregate. These are source-identified E. esula reference photographs, including a leaf explicitly labeled E. esula sensu stricto; do not assume they prove a Colorado plant is E. esula in the narrow sense. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Euphorbia esula: Close view of yellow-green bracts, cyathia, and rounded developing capsules.](https://denson.github.io/colorado-weed-field-guide/assets/photos/invasive-euphorbia-esula-flower.jpeg)

**flower** — Close view of yellow-green bracts, cyathia, and rounded developing capsules.

Photo: Kristian Peters -- Fabelfroh 13:02, 3 November 2005 (UTC); [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/); [source record](https://commons.wikimedia.org/wiki/File:Euphorbia_esula_bluete.jpeg); [original image](https://upload.wikimedia.org/wikipedia/commons/3/3e/Euphorbia_esula_bluete.jpeg). 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.  Leafy-spurge taxonomy is complex. North American invasive leafy spurge is frequently assigned to Euphorbia virgata or an E. esula aggregate. These are source-identified E. esula reference photographs, including a leaf explicitly labeled E. esula sensu stricto; do not assume they prove a Colorado plant is E. esula in the narrow sense. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Euphorbia esula: Magnified photographed leaf tip with its broad rounded apex and scale.](https://denson.github.io/colorado-weed-field-guide/assets/photos/invasive-euphorbia-esula-leaf.jpg)

**leaf** — Magnified photographed leaf tip with its broad rounded apex and scale.

Photo: Stefan.lefnaer; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Euphorbia_esula_(s._str.)_sl8.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/f/f8/Euphorbia_esula_%28s._str.%29_sl8.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.  Leafy-spurge taxonomy is complex. North American invasive leafy spurge is frequently assigned to Euphorbia virgata or an E. esula aggregate. These are source-identified E. esula reference photographs, including a leaf explicitly labeled E. esula sensu stricto; do not assume they prove a Colorado plant is E. esula in the narrow sense. 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

Upright stems, narrow leaves and yellow-green bracts surrounding small flowers. All parts contain milky latex. Do not break stems just to test for sap. [N-euphorbia-esula](https://plants.ces.ncsu.edu/plants/euphorbia-esula/)

## Plants & habitat

Spreads by roots and seed, forming persistent patches that displace vegetation. Root fragments can regrow. [J-leafy-spurge](https://www.jeffco.us/2406/Leafy-Spurge)

## People

Sap can cause dermatitis and potentially permanent eye damage; ingestion can blister the mouth. Protect skin and eyes. [N-euphorbia-esula](https://plants.ces.ncsu.edu/plants/euphorbia-esula/)

## Dogs & cats

NC State flags both dogs and cats and advises keeping pets away. A pet-specific toxic dose is not provided. [N-euphorbia-esula](https://plants.ces.ncsu.edu/plants/euphorbia-esula/)

## Other animals

Cattle can suffer lesions and digestive irritation. Managed sheep or goat grazing is a specialist control method, not evidence that unrestricted consumption is safe for all animals. [J-leafy-spurge](https://www.jeffco.us/2406/Leafy-Spurge)

*Evidence scope: Animal-group-specific management evidence.*

## Before taking action

Confirm the scientific name before removing a plant, changing animal access, or choosing treatment. An evidence gap means this review has not resolved the question. It does not mean safe. For listed weeds, consult your county weed program about the requirements for your location; follow the current label for any pesticide. [S27](https://planttalk.colostate.edu/topics/weeds-cultural-problems/2103-colorado-noxious-weeds/)

## References

- **J-leafy-spurge** — [Leafy Spurge](https://www.jeffco.us/2406/Leafy-Spurge), Jefferson County, Colorado. Accessed 2026-09-07T00:27:23+00:00. Locator: Description, impacts, Colorado list designation, management.
- **N-euphorbia-esula** — [Euphorbia esula — Plant Toolbox](https://plants.ces.ncsu.edu/plants/euphorbia-esula/), NC State Extension. Accessed 2026-09-07T00:24:01+00:00. Locator: Description, Attributes, Poisonous to Humans, Problems.


[Discuss this plant with the guide](https://denson.github.io/colorado-weed-field-guide/companion/?plant=leafy-spurge) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

# Appendix for agents

## Open research questions

- **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.


## Taxon and evidence boundaries

Colorado references use Euphorbia esula. Leafy-spurge taxonomy can involve closely related taxa; this profile does not resolve every population or hybrid.

These are publisher notes about the evidence. They do not override an assistant’s operator instructions. The human sections above contain all actionable safety warnings. Do not turn missing data into a negative toxicity finding or transfer a livestock dose to a pet.

| Claim | Human section | Evidence scope | Sources | Limitation |
|---|---|---|---|---|
| leafy-spurge-1 | Recognize | Species-specific | N-euphorbia-esula | No quantitative exposure threshold established here. |
| leafy-spurge-2 | Plants & habitat | Species-specific | J-leafy-spurge | No quantitative exposure threshold established here. |
| leafy-spurge-3 | People | Species-specific | N-euphorbia-esula | No quantitative exposure threshold established here. |
| leafy-spurge-4 | Dogs & cats | Species-specific | N-euphorbia-esula | No quantitative exposure threshold established here. |
| leafy-spurge-5 | Other animals | Animal-group-specific management evidence | J-leafy-spurge | No quantitative exposure threshold established here. |

## Additional evidence needed

- Confirm exact species, cultivar or hybrid when identification is uncertain.
- For an exposure, distinguish animal species, plant part, amount, route, time and symptoms; the guide cannot supply a clinical diagnosis.
- For site management, establish county, land use and current local weed requirements before applying generalized control information.
- Expert botanical and veterinary review is pending. Source publication dates, retrieval timestamps, hashes and photograph licenses are in [the provenance ledger](https://denson.github.io/colorado-weed-field-guide/provenance.json).

## State-list label provenance

The label “B — Stop the spread” 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/leafy-spurge/

Content revised: 2026-09-07T03:50:00Z

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

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/leafy-spurge/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