---
{
  "id": "showy-milkweed",
  "name": "Showy milkweed",
  "scientific": "Asclepias speciosa",
  "category": "native",
  "status": "Colorado native",
  "status_sources": [
    "S02",
    "S28"
  ],
  "warning": "Toxic if eaten",
  "warning_tone": "danger",
  "aliases": [],
  "taxonomy_note": "",
  "source_ids": [
    "S02",
    "S28",
    "S03",
    "S05",
    "S04"
  ],
  "description": "Showy milkweed: Toxic if eaten. Colorado identification, habitat and exposure evidence.",
  "claim_evidence": [
    {
      "label": "Recognize",
      "sources": [
        "S03"
      ],
      "scope": "Species-specific",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "showy-milkweed-1"
    },
    {
      "label": "Plants & habitat",
      "sources": [
        "S02"
      ],
      "scope": "Species-specific + garden judgment",
      "note": "Crowding advice is an editorial inference from self-seeding, not a measured allelopathy claim.",
      "reviewed": "2026-09-06",
      "id": "showy-milkweed-2"
    },
    {
      "label": "People",
      "sources": [
        "S05"
      ],
      "scope": "Genus-level",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "showy-milkweed-3"
    },
    {
      "label": "Dogs & cats",
      "sources": [
        "S04"
      ],
      "scope": "Genus-level",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "showy-milkweed-4"
    },
    {
      "label": "Other animals",
      "sources": [
        "S04",
        "S02"
      ],
      "scope": "Genus-level toxicity; species-specific benefit",
      "note": "",
      "reviewed": "2026-09-06",
      "id": "showy-milkweed-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": "Expert review",
        "question": "Obtain independent botanical and veterinary review of the identification and hazard summary.",
        "related_claim_ids": []
      }
    ],
    "expert_review": "pending"
  },
  "source": "content/plants/showy-milkweed.md"
}
---

# Showy milkweed

*Asclepias speciosa*

**Colorado native.** [S02](https://pueblo.extension.colostate.edu/low-water-native-plants-for-pollinators/) [S28](https://pueblo.extension.colostate.edu/loving-our-native-plants/)

> **Toxic if eaten.** 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. The cited findings are available 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.

![Asclepias speciosa: Close view of pale pink showy milkweed flowers, with long pointed hoods above reflexed petals.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-asclepias-speciosa-1.jpg)

**flowers** — Close view of pale pink showy milkweed flowers, with long pointed hoods above reflexed petals.

Photo: Andrey Zharkikh; [CC BY 2.0](https://creativecommons.org/licenses/by/2.0); [source record](https://commons.wikimedia.org/wiki/File:Asclepias_speciosa,_Red_Butte,_Utah.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/9/93/Asclepias_speciosa%2C_Red_Butte%2C_Utah.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.

![Asclepias speciosa: Pink and white showy milkweed flower cluster viewed from above, showing pointed hoods and unopened buds.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-asclepias-speciosa-2.jpg)

**flowers** — Pink and white showy milkweed flower cluster viewed from above, showing pointed hoods and unopened buds.

Photo: Tom Koerner / U.S. Fish and Wildlife Service; [Public domain](https://commons.wikimedia.org/wiki/Template:PD-USGov-FWS); [source record](https://commons.wikimedia.org/wiki/File:Asclepias_speciosa_at_Seedskadee_NWR_94_(48714355833).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/0/0d/Asclepias_speciosa_at_Seedskadee_NWR_94_%2848714355833%29.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.

![Asclepias speciosa: An open, rough-surfaced milkweed pod releasing brown seeds with silky white hairs.](https://denson.github.io/colorado-weed-field-guide/assets/photos/native-asclepias-speciosa-3.jpg)

**seed pod** — An open, rough-surfaced milkweed pod releasing brown seeds with silky white hairs.

Photo: John Rusk from Berkeley, CA, United States of America; [CC BY 2.0](https://creativecommons.org/licenses/by/2.0); [source record](https://commons.wikimedia.org/wiki/File:H20120920-5647%E2%80%94Asclepias_speciosa%E2%80%94RPBG_(9520794890).jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/6/6c/H20120920-5647%E2%80%94Asclepias_speciosa%E2%80%94RPBG_%289520794890%29.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

Pink flower clusters on an upright perennial; included in the Front Range native plant guide. [S03](https://www.extension.colostate.edu/docs/pubs/native/FrontRangeSm.pdf)

## Plants & habitat

Self-seeds and supports monarch caterpillars. Garden judgment: give volunteers room or manage seedlings beside smaller plants. [S02](https://pueblo.extension.colostate.edu/low-water-native-plants-for-pollinators/)

## People

Milkweed ingestion can cause serious poisoning; sap may irritate skin and eyes. Wear gloves when handling. [S05](https://www.poison.org/articles/milkweed-can-cause-serious-poisoning-204)

*Evidence scope: Genus-level.*

## Dogs & cats

Milkweeds are toxic to both. Signs can include vomiting and weakness, with potentially severe effects. Contact a veterinarian promptly after suspected ingestion. [S04](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/milkweed)

*Evidence scope: Genus-level.*

## Other animals

Milkweeds can poison horses and other livestock, while monarch caterpillars use this species as food. [S04](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/milkweed) [S02](https://pueblo.extension.colostate.edu/low-water-native-plants-for-pollinators/)

*Evidence scope: Genus-level toxicity; species-specific benefit.*

## 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

- **S02** — [Low Water Native Plants for Pollinators](https://pueblo.extension.colostate.edu/low-water-native-plants-for-pollinators/), CSU Extension · Pueblo County. Accessed 2026-09-07T00:23:52+00:00. Locator: Mid-Season Wildflowers: Showy Milkweed.
- **S28** — [Loving Our Native Plants](https://pueblo.extension.colostate.edu/loving-our-native-plants/), CSU Extension · Pueblo County. Accessed 2026-09-07T00:23:56+00:00. Locator: Native landscape plant list: Common sunflower and Showy milkweed.
- **S03** — [Low-Water Native Plants for Colorado Gardens: Front Range & Foothills](https://www.extension.colostate.edu/docs/pubs/native/FrontRangeSm.pdf), Colorado Native Plant Society / CSU Extension. Accessed 2026-09-07T00:23:53+00:00. Locator: Plant table: Asclepias speciosa and Achillea millefolium.
- **S05** — [Milkweed plants can cause serious poisoning](https://www.poison.org/articles/milkweed-can-cause-serious-poisoning-204), National Capital Poison Center. Accessed 2026-09-07T00:23:53+00:00. Locator: Symptoms; Effects on skin and in eyes; prevention.
- **S04** — [Milkweed](https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/milkweed), ASPCA Poison Control. Accessed 2026-09-07T00:23:52+00:00. Locator: Scientific Name; Toxicity; Clinical Signs; poison contact.


[Discuss this plant with the guide](https://denson.github.io/colorado-weed-field-guide/companion/?plant=showy-milkweed) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.

# Appendix for agents

## Open research questions

- **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 |
|---|---|---|---|---|
| showy-milkweed-1 | Recognize | Species-specific | S03 | No quantitative exposure threshold established here. |
| showy-milkweed-2 | Plants & habitat | Species-specific + garden judgment | S02 | Crowding advice is an editorial inference from self-seeding, not a measured allelopathy claim. |
| showy-milkweed-3 | People | Genus-level | S05 | No quantitative exposure threshold established here. |
| showy-milkweed-4 | Dogs & cats | Genus-level | S04 | No quantitative exposure threshold established here. |
| showy-milkweed-5 | Other animals | Genus-level toxicity; species-specific benefit | S04, S02 | 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/showy-milkweed/

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

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

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