---
{
  "id": "common-mullein",
  "name": "Common mullein",
  "scientific": "Verbascum thapsus",
  "category": "invasive",
  "status": "Colorado noxious weed · List C — Manage widespread weeds",
  "status_sources": [
    "CO-rules-2025"
  ],
  "warning": "Dense rosettes and persistent volunteers",
  "warning_tone": "caution",
  "aliases": [],
  "taxonomy_note": "Soft leaves do not establish medicinal or ingestion safety. This is not lamb’s-ear (Stachys byzantina).",
  "source_ids": [
    "CO-rules-2025",
    "N-verbascum-thapsus",
    "S27",
    "Fremont-list-definitions"
  ],
  "description": "Common mullein: Dense rosettes and persistent volunteers. Identification and evidence for Colorado readers.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "N-verbascum-thapsus"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "common-mullein-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "N-verbascum-thapsus"
      ],
      "scope": "Species-specific",
      "note": "",
      "id": "common-mullein-2"
    },
    {
      "label": "People",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "common-mullein-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "common-mullein-4"
    },
    {
      "label": "Other animals",
      "sources": [],
      "scope": "Review limitation",
      "note": "",
      "id": "common-mullein-5"
    },
    {
      "id": "common-mullein-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": "C",
  "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": [
          "common-mullein-3"
        ]
      },
      {
        "area": "Dogs & cats",
        "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.",
        "related_claim_ids": [
          "common-mullein-4"
        ]
      },
      {
        "area": "Other animals",
        "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.",
        "related_claim_ids": [
          "common-mullein-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": "C — Manage widespread weeds",
  "source": "content/plants/common-mullein.md"
}
---

# Common mullein

*Verbascum thapsus*

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

Widespread and well established. Control is recommended by the state; local governments may require management. 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).

> **Dense rosettes and persistent volunteers.** [Exposure help](https://denson.github.io/colorado-weed-field-guide/safety/).

**Identification caveat:** Soft leaves do not establish medicinal or ingestion safety. This is not lamb’s-ear (Stachys byzantina).

## 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.

![Verbascum thapsus: Tall yellow flowering spike above a column of broad pale woolly leaves.](https://denson.github.io/colorado-weed-field-guide/assets/photos/common-priority-photos-verbascum-thapsus-04-02-habit.jpg)

**habit** — Tall yellow flowering spike above a column of broad pale woolly leaves.

Photo: Isidre blanc; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:VERBASCUM_THAPSUS_-_B%C3%92FIA_-_IB-957_(Blenera).JPG); [original image](https://upload.wikimedia.org/wikipedia/commons/e/e6/VERBASCUM_THAPSUS_-_B%C3%92FIA_-_IB-957_%28Blenera%29.JPG). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Other mullein species and hybrids can resemble V. thapsus. Source-labeled V. phlomoides photographs found in gallery searches were not selected. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Verbascum thapsus: Small yellow flowers and pale woolly buds crowd a dense upright spike.](https://denson.github.io/colorado-weed-field-guide/assets/photos/common-priority-photos-verbascum-thapsus-04-08-flower.jpg)

**flower** — Small yellow flowers and pale woolly buds crowd a dense upright spike.

Photo: Fritz Geller-Grimm; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0); [source record](https://commons.wikimedia.org/wiki/File:Schwanheimer_Duene_fg14.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/f/fd/Schwanheimer_Duene_fg14.jpg). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Other mullein species and hybrids can resemble V. thapsus. Source-labeled V. phlomoides photographs found in gallery searches were not selected. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.

![Verbascum thapsus: Young basal rosette of thick oval gray-green leaves covered in soft woolly hairs.](https://denson.github.io/colorado-weed-field-guide/assets/photos/common-priority-photos-verbascum-thapsus-04-13-rosette.jpg)

**rosette** — Young basal rosette of thick oval gray-green leaves covered in soft woolly hairs.

Photo: Borealis55; [CC0](https://creativecommons.org/publicdomain/zero/1.0/deed.en); [source record](https://commons.wikimedia.org/wiki/File:Verbascum_thapsus_5799.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/4/48/Verbascum_thapsus_5799.jpg). Source page scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination. Other mullein species and hybrids can resemble V. thapsus. Source-labeled V. phlomoides photographs found in gallery searches were not selected. Wikimedia server-resized derivative; no crop, color change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.


## Recognize

A woolly leaf rosette produces a tall, dense spike of yellow flowers, typically in its second year. [N-verbascum-thapsus](https://plants.ces.ncsu.edu/plants/verbascum-thapsus/)

## Plants & habitat

Self-seeds in dry, disturbed places and can crowd neighboring vegetation. Prevent seed formation where control is needed. [N-verbascum-thapsus](https://plants.ces.ncsu.edu/plants/verbascum-thapsus/)

## 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-verbascum-thapsus** — [verbascum thapsus — Plant Toolbox](https://plants.ces.ncsu.edu/plants/verbascum-thapsus/), NC State Extension. Accessed 2026-09-07T01:04:55+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=common-mullein) — 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

Soft leaves do not establish medicinal or ingestion safety. This is not lamb’s-ear (Stachys byzantina).

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 |
|---|---|---|---|---|
| common-mullein-1 | Recognize | Species-specific | N-verbascum-thapsus | No quantitative safe exposure established here. |
| common-mullein-2 | Plants & habitat | Species-specific | N-verbascum-thapsus | No quantitative safe exposure established here. |
| common-mullein-3 | People | Review limitation | Review limitation | No quantitative safe exposure established here. |
| common-mullein-4 | Dogs & cats | Review limitation | Review limitation | No quantitative safe exposure established here. |
| common-mullein-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 “C — Manage widespread weeds” 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/common-mullein/

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

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

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