---
{
  "id": "snow-in-summer",
  "name": "Snow-in-summer",
  "scientific": "Cerastium tomentosum",
  "category": "xeriscape",
  "status": "Introduced garden groundcover",
  "status_sources": [
    "S12",
    "S11"
  ],
  "warning": "Spreading habit · Safety gap",
  "warning_tone": "caution",
  "aliases": [],
  "taxonomy_note": "",
  "source_ids": [
    "S12",
    "S11",
    "S25"
  ],
  "description": "Snow-in-summer: Spreading habit · Safety gap. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "S12",
        "S11"
      ],
      "scope": "Species-specific",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "snow-in-summer-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "S11",
        "S12"
      ],
      "scope": "Species-specific + garden judgment",
      "note": "Neighbor-crowding advice is inferred from aggressive, mat-forming growth.",
      "reviewed": "2026-09-06",
      "id": "snow-in-summer-2"
    },
    {
      "label": "People",
      "sources": [
        "S11",
        "S12"
      ],
      "scope": "Evidence gap",
      "note": "These horticultural profiles were not treated as toxicology clearance.",
      "reviewed": "2026-09-06",
      "id": "snow-in-summer-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "S11",
        "S12",
        "S25"
      ],
      "scope": "Evidence gap",
      "note": "No safety conclusion is inferred from omission from a toxic-plant list.",
      "reviewed": "2026-09-06",
      "id": "snow-in-summer-4"
    },
    {
      "label": "Other animals",
      "sources": [
        "S12"
      ],
      "scope": "Species-specific benefit; safety gap",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "snow-in-summer-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": [
          "snow-in-summer-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "snow-in-summer-4"
        ]
      },
      {
        "area": "Other animals",
        "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.",
        "related_claim_ids": [
          "snow-in-summer-5"
        ]
      },
      {
        "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/snow-in-summer.md"
}
---

# Snow-in-summer

*Cerastium tomentosum*

**Introduced garden groundcover.** [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/) [S11](https://extension.colostate.edu/resource/ground-cover-plants/)

> **Spreading habit · Safety gap.** Native status, garden use and noxious-weed class are separate from toxicity. [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

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

This is a sourced working profile. Evidence is incomplete for **People, Dogs & cats, Other animals**. 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.

![Several white flowers with deeply notched petals above gray-green foliage.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-cerastium-tomentosum-01.jpg)

**flower** — Several white flowers with deeply notched petals above gray-green foliage.

Photo: Salicyna; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Cerastium_tomentosum_2023-05-28_6525.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/8/8d/Cerastium_tomentosum_2023-05-28_6525.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.

![Entire slender flowering stem against the sky, with opposite narrow leaves and a few flowers near its top.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-cerastium-tomentosum-06.jpg)

**flowering stem** — Entire slender flowering stem against the sky, with opposite narrow leaves and a few flowers near its top.

Photo: Stefan.lefnaer; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Cerastium_tomentosum_sl5.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/f/f6/Cerastium_tomentosum_sl5.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.

![Source-assembled photographic plate showing narrow hairy leaves in opposite pairs on stems, with a 20 mm scale.](https://denson.github.io/colorado-weed-field-guide/assets/photos/xeriscape-cerastium-tomentosum-12.jpg)

**leaf and stem** — Source-assembled photographic plate showing narrow hairy leaves in opposite pairs on stems, with a 20 mm 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:Cerastium_tomentosum_sl21.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/e/ee/Cerastium_tomentosum_sl21.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

A low mat of woolly, pale foliage and white flowers. Originates in Italy; CSU lists it for hot, dry, sunny groundcover sites. [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/) [S11](https://extension.colostate.edu/resource/ground-cover-plants/)

## Plants & habitat

Spreads by underground runners and seed. CSU describes it as aggressive; garden judgment: keep it from overtaking smaller neighbors. [S11](https://extension.colostate.edu/resource/ground-cover-plants/) [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/)

## People

The sources used for this profile do not establish human ingestion safety. [S11](https://extension.colostate.edu/resource/ground-cover-plants/) [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/)

## Dogs & cats

No species-specific veterinary safety conclusion was established in this review. Do not interpret that gap as pet-safe. [S11](https://extension.colostate.edu/resource/ground-cover-plants/) [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/) [S25](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants)

## Other animals

Flowers attract bees. Safety for grazing animals is not established by the sources reviewed. [S12](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/)

## 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

- **S12** — [Cerastium tomentosum](https://plants.ces.ncsu.edu/plants/cerastium-tomentosum/), NC State Extension · Plant Toolbox. Accessed 2026-09-07T00:23:54+00:00. Locator: Description; origin; Wildlife Value.
- **S11** — [Ground Cover Plants](https://extension.colostate.edu/resource/ground-cover-plants/), Colorado State University Extension. Accessed 2026-09-07T00:23:54+00:00. Locator: Table 1b: hot, dry, sunny exposures; Cerastium tomentosum.
- **S25** — [Toxic and Non-Toxic Plants](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants), ASPCA Poison Control. Accessed 2026-09-07T00:23:56+00:00. Locator: Any plant material may cause vomiting or gastrointestinal upset; database limitations.


[Discuss this plant with the guide](https://denson.github.io/colorado-weed-field-guide/companion/?plant=snow-in-summer) — 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.
- **Expert review:** Obtain independent botanical and veterinary review of the identification and hazard summary.


## Taxon and evidence boundaries

Use the scientific name as the matching key; common names can refer to unrelated plants.

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 |
|---|---|---|---|---|
| snow-in-summer-1 | Recognize | Species-specific | S12, S11 | No quantitative exposure threshold established here. |
| snow-in-summer-2 | Plants & habitat | Species-specific + garden judgment | S11, S12 | Neighbor-crowding advice is inferred from aggressive, mat-forming growth. |
| snow-in-summer-3 | People | Evidence gap | S11, S12 | These horticultural profiles were not treated as toxicology clearance. |
| snow-in-summer-4 | Dogs & cats | Evidence gap | S11, S12, S25 | No safety conclusion is inferred from omission from a toxic-plant list. |
| snow-in-summer-5 | Other animals | Species-specific benefit; safety gap | S12 | 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/snow-in-summer/

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

Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/snow-in-summer/index.md

Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/snow-in-summer/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