---
{
  "id": "lewis-blue-flax",
  "name": "Lewis blue flax",
  "scientific": "Linum lewisii",
  "category": "xeriscape",
  "status": "Colorado native; low-water garden plant",
  "status_sources": [
    "C-perennials"
  ],
  "warning": "Ingestion and contact concerns",
  "warning_tone": "caution",
  "aliases": [
    "blue flax",
    "western blue flax"
  ],
  "taxonomy_note": "Use Linum lewisii records, not L. perenne or culinary flax L. usitatissimum. The source’s food-use language is not adopted as preparation advice.",
  "source_ids": [
    "C-perennials",
    "N-linum-lewisii"
  ],
  "description": "Lewis blue flax: Ingestion and contact concerns. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "N-linum-lewisii"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "lewis-blue-flax-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "N-linum-lewisii"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "lewis-blue-flax-2"
    },
    {
      "label": "People",
      "sources": [
        "N-linum-lewisii"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "lewis-blue-flax-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [],
      "scope": "Review limitation",
      "note": "Species-specific ingestion effects and exposure thresholds were not established in the reviewed sources.",
      "id": "lewis-blue-flax-4"
    },
    {
      "label": "Other animals",
      "sources": [
        "N-linum-lewisii"
      ],
      "scope": "Species-specific livestock warning",
      "note": "",
      "id": "lewis-blue-flax-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": [
          "lewis-blue-flax-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "lewis-blue-flax-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"
  },
  "source": "content/plants/lewis-blue-flax.md"
}
---

# Lewis blue flax

*Linum lewisii*

**Colorado native; low-water garden plant.** [C-perennials](https://extension.colostate.edu/resource/native-herbaceous-perennials-for-colorado-landscapes/)

> **Ingestion and contact concerns.** 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:** Use Linum lewisii records, not L. perenne or culinary flax L. usitatissimum. The source’s food-use language is not adopted as preparation advice.

## 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

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.

![Close view of slender narrow leaves along a green flax stem.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-linum-lewisii-01.jpg)

**leaf and stem** — Close view of slender narrow leaves along a green flax stem.

Photo: Walter Siegmund   (talk); [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Linum_lewisii_9746.JPG); [original image](https://upload.wikimedia.org/wikipedia/commons/0/03/Linum_lewisii_9746.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.

![Blue five-petaled flax flowers with pale veins and yellow centers, on a slender flowering stem.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-linum-lewisii-02.jpg)

**flower** — Blue five-petaled flax flowers with pale veins and yellow centers, on a slender flowering stem.

Photo: NPS / Jacob W. Frank; [Public domain](https://commons.wikimedia.org/wiki/File:Blue_Flax_-_Linum_lewisii_(37066946561).jpg#Licensing); [source record](https://commons.wikimedia.org/wiki/File:Blue_Flax_-_Linum_lewisii_(37066946561).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/1/18/Blue_Flax_-_Linum_lewisii_%2837066946561%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.

![Airy clump of thin stems carrying numerous blue flowers in dry grassland.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-linum-lewisii-03.jpg)

**habit** — Airy clump of thin stems carrying numerous blue flowers in dry grassland.

Photo: Skoch3; [CC BY-SA 3.0](http://creativecommons.org/licenses/by-sa/3.0/); [source record](https://commons.wikimedia.org/wiki/File:Linum_lewisii,_blue_flax,_Albuquerque.JPG); [original image](https://upload.wikimedia.org/wikipedia/commons/d/d0/Linum_lewisii%2C_blue_flax%2C_Albuquerque.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

Delicate five-petaled blue flowers above narrow leaves on slender stems. [N-linum-lewisii](https://plants.ces.ncsu.edu/plants/linum-lewisii/)

## Plants & habitat

A short-lived perennial that reseeds freely; reduce seed set if many volunteers are unwanted. It needs sun and drainage. [N-linum-lewisii](https://plants.ces.ncsu.edu/plants/linum-lewisii/)

## People

The source flags cyanogenic glycosides and contact dermatitis. This guide does not establish edible preparations or safe doses. [N-linum-lewisii](https://plants.ces.ncsu.edu/plants/linum-lewisii/)

## Dogs & cats

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

## Other animals

Large intake is reported as a concern for cattle and sheep, with potentially severe respiratory effects. Do not assume ornamental flax is suitable feed. [N-linum-lewisii](https://plants.ces.ncsu.edu/plants/linum-lewisii/)

## 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

- **C-perennials** — [Native Herbaceous Perennials for Colorado Landscapes](https://extension.colostate.edu/resource/native-herbaceous-perennials-for-colorado-landscapes/), Colorado State University Extension. Accessed 2026-09-07T00:27:17+00:00. Locator: Description, distribution, hazards, management; see claim locator.
- **N-linum-lewisii** — [Linum lewisii — Plant Toolbox](https://plants.ces.ncsu.edu/plants/linum-lewisii/), NC State Extension. Accessed 2026-09-07T00:23:59+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=lewis-blue-flax) — 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.
- **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

Use Linum lewisii records, not L. perenne or culinary flax L. usitatissimum. The source’s food-use language is not adopted as preparation advice.

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 |
|---|---|---|---|---|
| lewis-blue-flax-1 | Recognize | Species-specific | N-linum-lewisii | No quantitative exposure threshold established here. |
| lewis-blue-flax-2 | Plants & habitat | Species-specific | N-linum-lewisii | No quantitative exposure threshold established here. |
| lewis-blue-flax-3 | People | Species-specific | N-linum-lewisii | No quantitative exposure threshold established here. |
| lewis-blue-flax-4 | Dogs & cats | Review limitation | Review limitation | Species-specific ingestion effects and exposure thresholds were not established in the reviewed sources. |
| lewis-blue-flax-5 | Other animals | Species-specific livestock warning | N-linum-lewisii | 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).


---
Canonical HTML: https://denson.github.io/colorado-weed-field-guide/plants/lewis-blue-flax/

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

Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/lewis-blue-flax/index.md

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/lewis-blue-flax/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