---
{
  "id": "yellow-nutsedge",
  "name": "Yellow nutsedge",
  "scientific": "Cyperus esculentus",
  "category": "invasive",
  "status": "Colorado noxious weed · List B — Stop the spread",
  "status_sources": [
    "CO-rules-2025"
  ],
  "warning": "Underground tubers sustain infestations",
  "warning_tone": "caution",
  "aliases": [],
  "taxonomy_note": "This listed sedge is described as native in the NC source; that broad range label is not a Colorado nativity assessment. It is distinct from purple nutsedge (Cyperus rotundus).",
  "source_ids": [
    "CO-rules-2025",
    "N-cyperus-esculentus",
    "S27",
    "Fremont-list-definitions"
  ],
  "description": "Yellow nutsedge: Underground tubers sustain infestations. Identification and evidence for Colorado readers.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "N-cyperus-esculentus"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "yellow-nutsedge-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "N-cyperus-esculentus"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "yellow-nutsedge-2"
    },
    {
      "label": "People",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "yellow-nutsedge-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "yellow-nutsedge-4"
    },
    {
      "label": "Other animals",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "yellow-nutsedge-5"
    },
    {
      "id": "yellow-nutsedge-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": "People",
        "question": "Clarify the human exposure effects and evidence limits described in this section.",
        "related_claim_ids": [
          "yellow-nutsedge-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "yellow-nutsedge-4"
        ]
      },
      {
        "area": "Other animals",
        "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.",
        "related_claim_ids": [
          "yellow-nutsedge-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": "B — Stop the spread",
  "source": "content/plants/yellow-nutsedge.md"
}
---

# Yellow nutsedge

*Cyperus esculentus*

**Colorado noxious weed · List B — Stop the spread.** [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2)

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).

> **Underground tubers sustain infestations.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

**Identification caveat:** This listed sedge is described as native in the NC source; that broad range label is not a Colorado nativity assessment. It is distinct from purple nutsedge (Cyperus rotundus).

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

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

![Yellow nutsedge with upright leafy stems and radiating yellow-green spikelet clusters.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-bc-photos-cyperus-esculentus-02.jpg)

**habit** — Yellow nutsedge with upright leafy stems and radiating yellow-green spikelet clusters.

Photo: Krzysztof Ziarnek, Kenraiz; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Cyperus_esculentus_kz02.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/d/d1/Cyperus_esculentus_kz02.jpg). Source-identified photograph with visual consistency check Cyperus esculentus at Ridgemoor Country Club in Chicago, USA Source labeling and visible consistency checked; not an independent specimen determination. Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![A close view of harvested brown tiger-nut tubers of Cyperus esculentus.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-bc-photos-cyperus-esculentus-03.jpg)

**tubers** — A close view of harvested brown tiger-nut tubers of Cyperus esculentus.

Photo: Tamorlan; [CC BY 3.0](https://creativecommons.org/licenses/by/3.0); [source record](https://commons.wikimedia.org/wiki/File:Cyperus_esculentus_012.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/3/31/Cyperus_esculentus_012.jpg). Source-identified photograph with visual consistency check Tiger Nut Source labeling and visible consistency checked; not an independent specimen determination. Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![A yellow nutsedge inflorescence viewed from above, surrounded by long leaflike green bracts.](https://denson.github.io/colorado-weed-field-guide/assets/photos/list-bc-photos-cyperus-esculentus-09.jpg)

**inflorescence** — A yellow nutsedge inflorescence viewed from above, surrounded by long leaflike green bracts.

Photo: Homer Edward Price; [CC BY 2.0](https://creativecommons.org/licenses/by/2.0); [source record](https://commons.wikimedia.org/wiki/File:Yellow_Nutsedge_Cyperus_esculentus_(43998391481).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/4/4f/Yellow_Nutsedge_Cyperus_esculentus_%2843998391481%29.jpg). Source-identified photograph with visual consistency check Found in Oscar Scherer State Park, Florida Source labeling and visible consistency checked; not an independent specimen determination. Wikimedia-generated thumbnail rescaling only; downloaded bytes unchanged. Gallery display preserves the full image; the catalog preview uses a CSS crop.


## Recognize

A glossy, grass-like sedge with narrow, channeled leaves and triangular stems. Underground tubers are important identification features. [N-cyperus-esculentus](https://plants.ces.ncsu.edu/plants/cyperus-esculentus/)

## Plants & habitat

Rhizomes and tubers compete strongly with crops and can remain after shoots are pulled. Ordinary lawn-grass treatments may not control a sedge. [N-cyperus-esculentus](https://plants.ces.ncsu.edu/plants/cyperus-esculentus/)

## 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

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for dogs or cats. Missing evidence does not establish safety. 

## Other animals

The reviewed sources do not establish species-specific ingestion effects or a safe exposure amount for livestock. Missing evidence does not establish safety. 

## 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

- **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-cyperus-esculentus** — [cyperus esculentus — Plant Toolbox](https://plants.ces.ncsu.edu/plants/cyperus-esculentus/), NC State Extension. Accessed 2026-09-07T01:04:54+00:00. Locator: Description; Attributes; Problems; Poisonous to Humans.
- **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=yellow-nutsedge) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

# Appendix for agents

## 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.
- **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

This listed sedge is described as native in the NC source; that broad range label is not a Colorado nativity assessment. It is distinct from purple nutsedge (Cyperus rotundus).

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 |
|---|---|---|---|---|
| yellow-nutsedge-1 | Recognize | Species-specific | N-cyperus-esculentus | No quantitative safe exposure established here. |
| yellow-nutsedge-2 | Plants & habitat | Species-specific | N-cyperus-esculentus | No quantitative safe exposure established here. |
| yellow-nutsedge-3 | People | Review limitation | Review limitation | No quantitative safe exposure established here. |
| yellow-nutsedge-4 | Dogs & cats | Review limitation | Review limitation | No quantitative safe exposure established here. |
| yellow-nutsedge-5 | Other animals | Review limitation | Review limitation | 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 “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/yellow-nutsedge/

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

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

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/yellow-nutsedge/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