---
{
  "id": "buffalobur",
  "name": "Buffalobur",
  "scientific": "Solanum rostratum",
  "category": "native",
  "status": "Great Plains native; documented in Colorado",
  "status_sources": [
    "I-buffalobur",
    "U-buffalobur"
  ],
  "warning": "Sharp spines; toxic to livestock",
  "warning_tone": "caution",
  "aliases": [
    "buffalo-bur",
    "Colorado bur"
  ],
  "taxonomy_note": "Washington lists this plant as a noxious weed in that state. That legal designation is not transferred to Colorado.",
  "source_ids": [
    "I-buffalobur",
    "U-buffalobur",
    "W-buffalobur"
  ],
  "description": "Buffalobur: Sharp spines; toxic to livestock. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "I-buffalobur"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "buffalobur-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "W-buffalobur"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "buffalobur-2"
    },
    {
      "label": "People",
      "sources": [
        "I-buffalobur"
      ],
      "scope": "Documented spines; editorial risk inference",
      "note": "",
      "id": "buffalobur-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "W-buffalobur"
      ],
      "scope": "Physical-risk inference; pet evidence gap",
      "note": "",
      "id": "buffalobur-4"
    },
    {
      "label": "Other animals",
      "sources": [
        "W-buffalobur"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "buffalobur-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": [
          "buffalobur-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "buffalobur-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/buffalobur.md"
}
---

# Buffalobur

*Solanum rostratum*

**Great Plains native; documented in Colorado.** [I-buffalobur](https://crops.extension.iastate.edu/encyclopedia/buffalobur) [U-buffalobur](https://botany-server3.colorado.edu/collections/list.php?page=3&taxa=2365&taxontype=2&usethes=1)

> **Sharp spines; toxic to livestock.** 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:** Washington lists this plant as a noxious weed in that state. That legal designation is not transferred to Colorado.

## 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.

![Solanum rostratum: Deeply lobed leaves and prickly stems, with a yellow flower visible at the edge.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-solanum-rostratum-1.jpg)

**leaves and prickles** — Deeply lobed leaves and prickly stems, with a yellow flower visible at the edge.

Photo: Juan Carlos Fonseca Mata; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:Ayohuiztle_(Solanum_rostratum),_hoja.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/5/59/Ayohuiztle_%28Solanum_rostratum%29%2C_hoja.jpg). Wikimedia Commons source file title and species metadata identify the taxon. Visible morphology was checked for consistency, not treated as an independent botanical determination.   No edits to the downloaded image. Wikimedia may have supplied a scaled thumbnail; original and download URLs are recorded separately. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Solanum rostratum: Side view of a yellow buffalo-bur flower showing unequal stamens, hairy buds, and conspicuous prickles.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-solanum-rostratum-2.jpg)

**flower detail** — Side view of a yellow buffalo-bur flower showing unequal stamens, hairy buds, and conspicuous prickles.

Photo: Dcrjsr; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0); [source record](https://commons.wikimedia.org/wiki/File:Buffalo_berry_Solanum_rostratum_flower_close.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/5/55/Buffalo_berry_Solanum_rostratum_flower_close.jpg). Wikimedia Commons source file title and species metadata identify the taxon. Visible morphology was checked for consistency, not treated as an independent botanical determination.   No edits to the downloaded image. Wikimedia may have supplied a scaled thumbnail; original and download URLs are recorded separately. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Solanum rostratum: A spreading buffalo-bur plant in rocky soil, with lobed leaves, yellow flowers, and spiny fruiting structures.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-solanum-rostratum-3.jpg)

**whole plant** — A spreading buffalo-bur plant in rocky soil, with lobed leaves, yellow flowers, and spiny fruiting structures.

Photo: Dcrjsr; [CC BY 4.0](https://creativecommons.org/licenses/by/4.0); [source record](https://commons.wikimedia.org/wiki/File:Buffalo_berry_Solanum_rostratum_plant.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/d/d0/Buffalo_berry_Solanum_rostratum_plant.jpg). Wikimedia Commons source file title and species metadata identify the taxon. Visible morphology was checked for consistency, not treated as an independent botanical determination.   No edits to the downloaded image. Wikimedia may have supplied a scaled thumbnail; original and download URLs are recorded separately. Gallery display preserves the full image; the catalog preview uses a CSS crop.


## Recognize

Yellow, five-lobed flowers; deeply lobed leaves with conspicuous spines on the veins and stems. This is an annual. [I-buffalobur](https://crops.extension.iastate.edu/encyclopedia/buffalobur)

## Plants & habitat

Can compete strongly with forage in disturbed pastures. Prevent seed production where removal is needed. [W-buffalobur](https://www.nwcb.wa.gov/weeds/buffalobur)

## People

The abundant spines present a puncture hazard. Use sturdy gloves for removal; this is a physical-risk inference from the documented spines. Human ingestion effects are not established here. [I-buffalobur](https://crops.extension.iastate.edu/encyclopedia/buffalobur)

*Evidence scope: Documented spines; editorial risk inference.*

## Dogs & cats

Spines may injure paws or mouths. Pet-specific chemical toxicity is not established by the livestock source; prevent chewing. [W-buffalobur](https://www.nwcb.wa.gov/weeds/buffalobur)

*Evidence scope: Physical-risk inference; pet evidence gap.*

## Other animals

Reported toxic to livestock; burs also catch in sheep wool. [W-buffalobur](https://www.nwcb.wa.gov/weeds/buffalobur)

## 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

- **I-buffalobur** — [Buffalobur](https://crops.extension.iastate.edu/encyclopedia/buffalobur), Iowa State University Extension. Accessed 2026-09-07T00:27:17+00:00. Locator: Description, distribution, hazards, management; see claim locator.
- **U-buffalobur** — [Solanum rostratum herbarium collection records](https://botany-server3.colorado.edu/collections/list.php?page=3&taxa=2365&taxontype=2&usethes=1), University of Colorado Museum of Natural History. Accessed 2026-09-07. Locator: COLO:V specimens 00785139 and 00785204; Colorado localities.
- **W-buffalobur** — [Buffalobur](https://www.nwcb.wa.gov/weeds/buffalobur), Washington State Noxious Weed Control Board. Accessed 2026-09-07T00:27:17+00:00. Locator: Description, distribution, hazards, management; see claim locator.


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

Washington lists this plant as a noxious weed in that state. That legal designation is not transferred to Colorado.

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 |
|---|---|---|---|---|
| buffalobur-1 | Recognize | Species-specific | I-buffalobur | No quantitative exposure threshold established here. |
| buffalobur-2 | Plants & habitat | Species-specific | W-buffalobur | No quantitative exposure threshold established here. |
| buffalobur-3 | People | Documented spines; editorial risk inference | I-buffalobur | No quantitative exposure threshold established here. |
| buffalobur-4 | Dogs & cats | Physical-risk inference; pet evidence gap | W-buffalobur | No quantitative exposure threshold established here. |
| buffalobur-5 | Other animals | Species-specific | W-buffalobur | 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/buffalobur/

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

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

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