---
{
  "id": "fernleaf-yarrow",
  "name": "Fernleaf yarrow",
  "scientific": "Achillea filipendulina",
  "category": "xeriscape",
  "status": "Introduced drought-tolerant perennial",
  "status_sources": [
    "N-achillea-filipendulina"
  ],
  "warning": "Spreads; pet toxicity unresolved",
  "warning_tone": "caution",
  "aliases": [],
  "taxonomy_note": "Do not merge this taxon with Achillea millefolium solely because both are called yarrow.",
  "source_ids": [
    "N-achillea-filipendulina",
    "S08"
  ],
  "description": "Fernleaf yarrow: Spreads; pet toxicity unresolved. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "N-achillea-filipendulina"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "fernleaf-yarrow-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "N-achillea-filipendulina"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "fernleaf-yarrow-2"
    },
    {
      "label": "People",
      "sources": [],
      "scope": "Review limitation",
      "note": "This species-specific horticultural source does not establish human ingestion safety.",
      "id": "fernleaf-yarrow-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "S08"
      ],
      "scope": "Different-species source; unresolved transfer",
      "note": "",
      "id": "fernleaf-yarrow-4"
    },
    {
      "label": "Other animals",
      "sources": [],
      "scope": "Review limitation",
      "note": "Species-specific ingestion effects and exposure thresholds were not established in the reviewed sources.",
      "id": "fernleaf-yarrow-5"
    }
  ],
  "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": [
          "fernleaf-yarrow-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "fernleaf-yarrow-4"
        ]
      },
      {
        "area": "Other animals",
        "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.",
        "related_claim_ids": [
          "fernleaf-yarrow-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"
  },
  "source": "content/plants/fernleaf-yarrow.md"
}
---

# Fernleaf yarrow

*Achillea filipendulina*

**Introduced drought-tolerant perennial.** [N-achillea-filipendulina](https://plants.ces.ncsu.edu/plants/achillea-filipendulina/)

> **Spreads; pet toxicity unresolved.** 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:** Do not merge this taxon with Achillea millefolium solely because both are called yarrow.

## 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

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.

![Macro view of a domed-to-flat cluster of small golden-yellow flower heads.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-achillea-filipendulina-01.jpg)

**flower** — Macro view of a domed-to-flat cluster of small golden-yellow flower heads.

Photo: Yerpo; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Achillea_filipendulina_flowers.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/3/3b/Achillea_filipendulina_flowers.jpg). Source-supported identification with visual consistency check Photo selection verifies source labeling and visible consistency; it is not an independent specimen determination.  Downloaded source thumbnail; no further pixel edits. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Upright yellow-flowering yarrow in bare stony soil, with fernlike divided leaves visible down the stems.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-achillea-filipendulina-02.jpg)

**habit and leaf** — Upright yellow-flowering yarrow in bare stony soil, with fernlike divided leaves visible down the stems.

Photo: Stefan.lefnaer; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Achillea_filipendulina_sl1.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/d/d4/Achillea_filipendulina_sl1.jpg). Source-supported identification with visual consistency check Photo selection verifies source labeling and visible consistency; it is not an independent specimen determination.  Downloaded source thumbnail; no further pixel edits. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Tall garden clump with many flat golden-yellow flower clusters above fernlike green foliage.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-achillea-filipendulina-03.jpg)

**garden habit** — Tall garden clump with many flat golden-yellow flower clusters above fernlike green foliage.

Photo: Andrea Moro; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Achillea_filipendulina_plant_(01).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/f/fa/Achillea_filipendulina_plant_%2801%29.jpg). Source-supported identification with visual consistency check Photo selection verifies source labeling and visible consistency; it is not an independent specimen determination.  Downloaded source thumbnail; no further pixel edits. Gallery display preserves the full image; the catalog preview uses a CSS crop.


## Recognize

Tall stems hold flat yellow flower clusters above fern-like green leaves. [N-achillea-filipendulina](https://plants.ces.ncsu.edu/plants/achillea-filipendulina/)

## Plants & habitat

Tolerates dry sites and can crowd its space; divide as needed and avoid overwatering. Cultivars differ in seed production. [N-achillea-filipendulina](https://plants.ces.ncsu.edu/plants/achillea-filipendulina/)

## People

This species-specific horticultural source does not establish human ingestion safety. This is an evidence gap, not proof of safety.

## Dogs & cats

The ASPCA yarrow entry names Achillea millefolium. It does not resolve toxicity for A. filipendulina; prevent chewing while this gap remains. [S08](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/yarrow)

## Other animals

Species-specific ingestion effects and exposure thresholds were not established in the reviewed sources. This is an evidence gap, not proof of safety.

## 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

- **N-achillea-filipendulina** — [Achillea filipendulina — Plant Toolbox](https://plants.ces.ncsu.edu/plants/achillea-filipendulina/), NC State Extension. Accessed 2026-09-07T00:23:59+00:00. Locator: Description, Attributes, Poisonous to Humans, Problems.
- **S08** — [Yarrow](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/yarrow), ASPCA Poison Control. Accessed 2026-09-07T00:23:53+00:00. Locator: Scientific Name; Toxicity; Clinical Signs.


[Discuss this plant with the guide](https://denson.github.io/colorado-weed-field-guide/companion/?plant=fernleaf-yarrow) — 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.


## Taxon and evidence boundaries

Do not merge this taxon with Achillea millefolium solely because both are called yarrow.

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 |
|---|---|---|---|---|
| fernleaf-yarrow-1 | Recognize | Species-specific | N-achillea-filipendulina | No quantitative exposure threshold established here. |
| fernleaf-yarrow-2 | Plants & habitat | Species-specific | N-achillea-filipendulina | No quantitative exposure threshold established here. |
| fernleaf-yarrow-3 | People | Review limitation | Review limitation | This species-specific horticultural source does not establish human ingestion safety. |
| fernleaf-yarrow-4 | Dogs & cats | Different-species source; unresolved transfer | S08 | No quantitative exposure threshold established here. |
| fernleaf-yarrow-5 | Other animals | Review limitation | Review limitation | Species-specific ingestion effects and exposure thresholds were not established in the reviewed sources. |

## 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).


---
Canonical HTML: https://denson.github.io/colorado-weed-field-guide/plants/fernleaf-yarrow/

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

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

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/fernleaf-yarrow/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