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# Native volunteers

Native plants that can volunteer or spread where they are not wanted. Their ecological value and their hazards deserve separate consideration. Regional and taxonomic limits are explained in the profiles.

29 plants in this view; 154 profiles and 462 photographs in the guide.

[Biggest concerns](https://denson.github.io/colorado-weed-field-guide/biggest-concerns/) · [Coverage: all 82 state-list entries](https://denson.github.io/colorado-weed-field-guide/coverage/) · [Exposure and safety guide](https://denson.github.io/colorado-weed-field-guide/safety/) · [Learn to use this guide](https://denson.github.io/colorado-weed-field-guide/companion/)

## Native volunteers

- [Black greasewood](https://denson.github.io/colorado-weed-field-guide/plants/black-greasewood/) — *Sarcobatus vermiculatus*. **Oxalate poisoning can be fatal to livestock**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/black-greasewood/index.md).
  ![Low, spreading greasewood shrub with dense green foliage in open dry ground.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/black-greasewood.webp) Photo: John Gaskin; CC0 1.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/black-greasewood/).
- [Broom snakeweed](https://denson.github.io/colorado-weed-field-guide/plants/broom-snakeweed/) — *Gutierrezia sarothrae*. **Livestock poisoning and abortion risk when heavily eaten**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/broom-snakeweed/index.md).
  ![Small branching broom snakeweed plant with yellow flower clusters above a woody base on rocky ground.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/broom-snakeweed.webp) Photo: CK2AZ; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/broom-snakeweed/).
- [Buffalobur](https://denson.github.io/colorado-weed-field-guide/plants/buffalobur/) — *Solanum rostratum*. **Sharp spines; toxic to livestock**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/buffalobur/index.md).
  ![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/thumbs/buffalobur.webp) Photo: Juan Carlos Fonseca Mata; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/buffalobur/).
- [Canada goldenrod](https://denson.github.io/colorado-weed-field-guide/plants/canada-goldenrod/) — *Solidago canadensis*. **Spreads by roots and seed**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/canada-goldenrod/index.md).
  ![Solidago canadensis: A goldenrod stem with a branching yellow flower plume and narrow, alternate toothed leaves.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/canada-goldenrod.webp) Photo: Étienne Lacroix-Carignan; CC0 1.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/canada-goldenrod/).
- [Catchweed bedstraw](https://denson.github.io/colorado-weed-field-guide/plants/catchweed-bedstraw/) — *Galium aparine*. **Hooked hairs and burrs cling to fur and clothing**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/catchweed-bedstraw/index.md).
  ![Galium aparine: Small white flowers and rounded young fruits at the tip of a prickly leafy shoot.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/catchweed-bedstraw.webp) Photo: Krzysztof Ziarnek, Kenraiz; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/catchweed-bedstraw/).
- [Common blue violet](https://denson.github.io/colorado-weed-field-guide/plants/common-blue-violet/) — *Viola sororia*. **A native volunteer; identify the species before removing**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/common-blue-violet/index.md).
  ![Common blue violet: a single violet flower with purple-and-pale petals and darker veins leading toward its center.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/common-blue-violet.webp) Photo: James Steakley; CC BY-SA 3.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/common-blue-violet/).
- [Common ragweed](https://denson.github.io/colorado-weed-field-guide/plants/common-ragweed/) — *Ambrosia artemisiifolia*. **Pollen allergy; skin irritation**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/common-ragweed/index.md).
  ![Ambrosia artemisiifolia: A low stand of common ragweed flowering along the edge of a paved path, with other vegetation nearby.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/common-ragweed.webp) Photo: Ayotte, Gilles, 1948-; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/common-ragweed/).
- [Common sunflower](https://denson.github.io/colorado-weed-field-guide/plants/common-sunflower/) — *Helianthus annuus*. **Listed non-toxic to dogs & cats**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/common-sunflower/index.md).
  ![Helianthus annuus: Front view of a sunflower head, showing yellow ray florets surrounding the darker central disk.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/common-sunflower.webp) Photo: Michelle W. （鍾偉瑋）; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/common-sunflower/).
- [Curlycup gumweed](https://denson.github.io/colorado-weed-field-guide/plants/curlycup-gumweed/) — *Grindelia squarrosa*. **Sticky resin and conditional selenium concern**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/curlycup-gumweed/index.md).
  ![Rounded, densely branching curlycup gumweed plant covered with yellow flower heads.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/curlycup-gumweed.webp) Photo: Jesse Grove; CC0 1.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/curlycup-gumweed/).
- [Foxtail barley](https://denson.github.io/colorado-weed-field-guide/plants/foxtail-barley/) — *Hordeum jubatum*. **Barbed seed awns injure animals**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/foxtail-barley/index.md).
  ![Hordeum jubatum: A tuft of foxtail barley with slender leaves and pale pink, long-awned heads.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/foxtail-barley.webp) Photo: Diego Delso; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/foxtail-barley/).
- [Giant ragweed](https://denson.github.io/colorado-weed-field-guide/plants/giant-ragweed/) — *Ambrosia trifida*. **Allergenic pollen and strong competition in disturbed ground**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/giant-ragweed/index.md).
  ![Ambrosia trifida: An upright giant ragweed plant beside a fence, with large three- to five-lobed leaves.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/giant-ragweed.webp) Photo: GTBacchus; CC BY-SA 3.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/giant-ragweed/).
- [Golden banner](https://denson.github.io/colorado-weed-field-guide/plants/golden-banner/) — *Thermopsis divaricarpa*. **May poison livestock**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/golden-banner/index.md).
  ![Thermopsis divaricarpa: An upright shoot with yellow flower buds and emerging flowers above leafy nodes and broad stipules.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/golden-banner.webp) Photo: Laura J. Costello; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/golden-banner/).
- [Hemp dogbane](https://denson.github.io/colorado-weed-field-guide/plants/hemp-dogbane/) — *Apocynum cannabinum*. **Cardiac-glycoside poisoning hazard for people and animals**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/hemp-dogbane/index.md).
  ![Apocynum cannabinum: A dense leafy flowering stand beside a cultivated field.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/hemp-dogbane.webp) Photo: Ayotte, Gilles, 1948-; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/hemp-dogbane/).
- [Horseweed](https://denson.github.io/colorado-weed-field-guide/plants/horseweed/) — *Erigeron canadensis*. **Fast windborne spread; some populations resist herbicides**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/horseweed/index.md).
  ![Erigeron canadensis: A tall upright stem topped by a broad, finely branched pale mature head cluster.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/horseweed.webp) Photo: Enrico Blasutto; CC BY-SA 3.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/horseweed/).
- [Low larkspur](https://denson.github.io/colorado-weed-field-guide/plants/low-larkspur/) — *Delphinium nuttallianum*. **Serious livestock and pet poisoning hazard**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/low-larkspur/index.md).
  ![Delphinium nuttallianum: A patch of low blue-flowered larkspur growing among stones and dry leaf litter.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/low-larkspur.webp) Photo: NPS; Public domain. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/low-larkspur/).
- [Meadow death camas](https://denson.github.io/colorado-weed-field-guide/plants/meadow-death-camas/) — *Toxicoscordion venenosum*. **Potentially fatal ingestion; onion-like bulbs**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/meadow-death-camas/index.md).
  ![Toxicoscordion venenosum: An upright cluster of small pale flowers above a basal group of narrow, strap-shaped leaves.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/meadow-death-camas.webp) Photo: NPS Photo; Public domain. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/meadow-death-camas/).
- [Netseed lambsquarters](https://denson.github.io/colorado-weed-field-guide/plants/netseed-lambsquarters/) — *Chenopodium berlandieri*. **A fast-growing volunteer; pet toxicity remains unresolved**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/netseed-lambsquarters/index.md).
  ![Pitseed goosefoot: a small upright leafy goosefoot plant growing among stones in open ground.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/netseed-lambsquarters.webp) Photo: Matt Lavin; CC BY-SA 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/netseed-lambsquarters/).
- [Prairie sage](https://denson.github.io/colorado-weed-field-guide/plants/prairie-sage/) — *Artemisia ludoviciana*. **Spreading roots; pet evidence gap**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/prairie-sage/index.md).
  ![Artemisia ludoviciana: Dense, silvery foliage with narrow leaves, some divided into slender lobes.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/prairie-sage.webp) Photo: Matt Lavin from Bozeman, Montana, USA; CC BY-SA 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/prairie-sage/).
- [Showy milkweed](https://denson.github.io/colorado-weed-field-guide/plants/showy-milkweed/) — *Asclepias speciosa*. **Toxic if eaten**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/showy-milkweed/index.md).
  ![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/thumbs/showy-milkweed.webp) Photo: Andrey Zharkikh; CC BY 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/showy-milkweed/).
- [Silverleaf nightshade](https://denson.github.io/colorado-weed-field-guide/plants/silverleaf-nightshade/) — *Solanum elaeagnifolium*. **Toxic leaves and berries; persistent spreading roots**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/silverleaf-nightshade/index.md).
  ![Upright silverleaf nightshade stem with gray-green leaves and purple flowers in a grassy field.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/silverleaf-nightshade.webp) Photo: Sam Kieschnick; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/silverleaf-nightshade/).
- [Snow-on-the-mountain](https://denson.github.io/colorado-weed-field-guide/plants/snow-on-the-mountain/) — *Euphorbia marginata*. **Latex can damage skin and eyes; toxic if eaten**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/snow-on-the-mountain/index.md).
  ![Tall, branching snow-on-the-mountain plant with green lower leaves and white-edged upper foliage.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/snow-on-the-mountain.webp) Photo: Mark G; CC0 1.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/snow-on-the-mountain/).
- [Spotted spurge](https://denson.github.io/colorado-weed-field-guide/plants/spotted-spurge/) — *Euphorbia maculata*. **Milky sap can injure skin and eyes; keep pets from chewing**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/spotted-spurge/index.md).
  ![Spotted spurge: low radiating reddish stems and small opposite leaves form a mat on stony ground.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/spotted-spurge.webp) Photo: Stefan.lefnaer; CC BY-SA 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/spotted-spurge/).
- [Stinging nettle](https://denson.github.io/colorado-weed-field-guide/plants/stinging-nettle/) — *Urtica dioica*. **Stinging hairs; this profile covers a taxonomic complex**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/stinging-nettle/index.md).
  ![Urtica dioica: An upright nettle stem bearing toothed opposite leaves and slender branching flower clusters.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/stinging-nettle.webp) Photo: Przykuta; CC BY-SA 3.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/stinging-nettle/).
- [Tall larkspur](https://denson.github.io/colorado-weed-field-guide/plants/tall-larkspur/) — *Delphinium barbeyi*. **Serious livestock and pet poisoning hazard**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/tall-larkspur/index.md).
  ![Delphinium barbeyi: A blue-flowered larkspur stem with several spurred flowers and divided stem leaves.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/tall-larkspur.webp) Photo: Ms. Sticky; CC BY 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/tall-larkspur/).
- [Western poison ivy](https://denson.github.io/colorado-weed-field-guide/plants/western-poison-ivy/) — *Toxicodendron rydbergii*. **Skin-rash oil can travel on pet fur**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/western-poison-ivy/index.md).
  ![Toxicodendron rydbergii: Dense cluster of pale whitish berries among dry leaves and twigs.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/western-poison-ivy.webp) Photo: Andrey Zharkikh from Salt Lake City, USA; CC BY 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/western-poison-ivy/).
- [Western ragweed](https://denson.github.io/colorado-weed-field-guide/plants/western-ragweed/) — *Ambrosia psilostachya*. **A persistent perennial ragweed; allergy detail still under review**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/western-ragweed/index.md).
  ![Upright western ragweed stems with divided green leaves and elongated terminal flower spikes.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/western-ragweed.webp) Photo: Zihao Wang; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/western-ragweed/).
- [Western water hemlock](https://denson.github.io/colorado-weed-field-guide/plants/western-water-hemlock/) — *Cicuta douglasii*. **Potentially fatal poisoning; wetland look-alike danger**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/western-water-hemlock/index.md).
  ![Cicuta douglasii: Upright leafy stems with pinnately divided, sharply toothed leaflets.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/western-water-hemlock.webp) Photo: Lee Cain; CC BY 4.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/western-water-hemlock/).
- [Western whorled milkweed](https://denson.github.io/colorado-weed-field-guide/plants/western-whorled-milkweed/) — *Asclepias subverticillata*. **High livestock toxicity**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/western-whorled-milkweed/index.md).
  ![Asclepias subverticillata: Several slender flowering stems with small white umbels and very narrow leaves.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/western-whorled-milkweed.webp) Photo: Patrick Alexander from Las Cruces, NM; CC0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/western-whorled-milkweed/).
- [White locoweed](https://denson.github.io/colorado-weed-field-guide/plants/white-locoweed/) — *Oxytropis sericea*. **Toxic to livestock**. [Full Markdown profile](https://denson.github.io/colorado-weed-field-guide/plants/white-locoweed/index.md).
  ![Oxytropis sericea: Dry tan pods clustered along a stalk, some split open near their tips.](https://denson.github.io/colorado-weed-field-guide/assets/thumbs/white-locoweed.webp) Photo: Matt Lavin from Bozeman, Montana, USA; CC BY-SA 2.0. [Photo credits and sources](https://denson.github.io/colorado-weed-field-guide/plants/white-locoweed/).


# Appendix for agents

Category membership is editorial navigation. Native plants can also be xeriscape plants; noxious-list class is separate from toxicity. Follow the individual profiles for claim scope, caveats, and photo attribution. This is a selected catalog, not the entire Colorado flora.


---
Canonical HTML: https://denson.github.io/colorado-weed-field-guide/native/

Content revised: 2026-09-21T19:48:00Z

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

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