--- { "id": "yellow-sweetclover", "name": "Yellow sweetclover", "scientific": "Melilotus officinalis", "category": "invasive", "status": "Common introduced weed · not on state Lists A/B/C", "status_sources": [ "C-floristic-2020", "CO-rules-2025" ], "warning": "Moldy sweetclover hay can cause dangerous bleeding", "warning_tone": "caution", "aliases": [ "yellow sweet clover" ], "taxonomy_note": "", "source_ids": [ "C-floristic-2020", "CO-rules-2025", "N-melilotus-officinalis", "F-melilotus", "C-descriptions", "S27" ], "description": "Yellow sweetclover: Moldy sweetclover hay can cause dangerous bleeding. Identification and evidence for Colorado readers.", "claim_evidence": [ { "label": "Identification", "sources": [ "N-melilotus-officinalis", "F-melilotus" ], "scope": "Species-specific", "note": "", "id": "yellow-sweetclover-1" }, { "label": "People", "sources": [], "scope": "Review limitation", "note": "", "id": "yellow-sweetclover-2" }, { "label": "Dogs & cats", "sources": [], "scope": "Review limitation", "note": "", "id": "yellow-sweetclover-3" }, { "label": "Other animals", "sources": [ "F-melilotus" ], "scope": "Sweetclover group evidence", "note": "", "id": "yellow-sweetclover-4" }, { "label": "Plants & habitat", "sources": [ "N-melilotus-officinalis" ], "scope": "Species-specific", "note": "", "id": "yellow-sweetclover-5" }, { "label": "Management & timing", "sources": [ "C-descriptions", "F-melilotus" ], "scope": "Management synthesis", "note": "", "id": "yellow-sweetclover-6" } ], "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": [ "yellow-sweetclover-2" ] }, { "area": "Dogs & cats", "question": "Find species-specific dog and cat exposure evidence; do not infer safety from missing reports.", "related_claim_ids": [ "yellow-sweetclover-3" ] }, { "area": "Other animals", "question": "Clarify feeding and exposure risks for each animal group; do not transfer findings between species.", "related_claim_ids": [ "yellow-sweetclover-4" ] }, { "area": "Expert review", "question": "Obtain independent botanical and veterinary review of the identification and hazard summary.", "related_claim_ids": [] } ], "expert_review": "pending" }, "colorado_relevance": { "source_id": "C-floristic-2020", "locator": "Appendix B; PDF page 63; Melilotus officinalis", "basis": "Included in the 2020 statewide flora assessment. This is not a current county abundance survey.", "source_taxon": "Melilotus officinalis" }, "source": "content/plants/yellow-sweetclover.md" } --- # Yellow sweetclover *Melilotus officinalis* **Common introduced weed · not on state Lists A/B/C.** [C-floristic-2020](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf) [CO-rules-2025](https://www.sos.state.co.us/CCR/GenerateRulePdf.do?ruleVersionId=11948&fileName=8+CCR+1206-2) > **Moldy sweetclover hay can cause dangerous bleeding.** [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 Source-identified reference photographs; these are not a complete identification key. A source location outside Colorado does not establish local occurrence. ![Yellow sweetclover: small yellow pea-like flowers hang along a narrow elongated raceme.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-garden-photos-melilotus-officinalis-08-01-flower.jpg) **flower** — Small yellow pea-like flowers hang along a narrow elongated raceme. Photo: Isidre blanc; [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0); [source record](https://commons.wikimedia.org/wiki/File:MELILOTUS_OFFICINALIS_-_LLANERA_-_IB-549_(Melilot).JPG); [original image](https://upload.wikimedia.org/wikipedia/commons/5/55/MELILOTUS_OFFICINALIS_-_LLANERA_-_IB-549_%28Melilot%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. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific. Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop. ![Yellow sweetclover: a branching leafy plant with many slender yellow flower racemes at a path edge.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-garden-photos-melilotus-officinalis-08-11-habit.jpg) **habit** — A branching leafy plant with many slender yellow flower racemes at a path edge. Photo: Rasbak; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/); [source record](https://commons.wikimedia.org/wiki/File:Melilotus_officinalis_Citroengele_honingklaver_plant.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/a/a4/Melilotus_officinalis_Citroengele_honingklaver_plant.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. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific. Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop. ![Yellow sweetclover: compound leaves with three finely toothed leaflets along upright branching green stems.](https://denson.github.io/colorado-weed-field-guide/assets/photos/coverage-garden-photos-melilotus-officinalis-08-13-foliage.jpg) **foliage** — Compound leaves with three finely toothed leaflets along upright branching green stems. Photo: Rasbak; [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/); [source record](https://commons.wikimedia.org/wiki/File:Melilotus_officinalis_Citroengele_honingklaver_blad.jpg); [original image](https://upload.wikimedia.org/wikipedia/commons/a/a9/Melilotus_officinalis_Citroengele_honingklaver_blad.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. Source-identified M. officinalis. Related yellow-flowered sweetclovers require reproductive characters for confident determination; flower color by itself is not species-specific. Wikimedia server-resized derivative, reduced from the original; no crop, color change, upscaling, or generative editing. Gallery display preserves the full image; catalog preview may use a CSS crop. ## Identification An upright, usually biennial legume with three leaflets and elongated clusters of small yellow flowers. Fresh flower color separates it from white sweetclover. [N-melilotus-officinalis](https://plants.ces.ncsu.edu/plants/melilotus-officinalis/) [F-melilotus](https://research.fs.usda.gov/feis/species-reviews/melspp) ## 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 Improperly cured or moldy sweetclover hay can develop compounds that impair clotting, causing severe internal bleeding. Diets dominated by sweetclover also carry a livestock bloat risk. These findings do not establish pet exposure limits. [F-melilotus](https://research.fs.usda.gov/feis/species-reviews/melspp) *Evidence scope: Sweetclover group evidence.* ## Plants & habitat It fixes nitrogen and feeds pollinators, but can spread beyond plantings. Its deep taproot helps established plants tolerate dry conditions. [N-melilotus-officinalis](https://plants.ces.ncsu.edu/plants/melilotus-officinalis/) ## Management & timing Prevent flowering and reseeding where unwanted. Have suspect hay assessed before feeding it. [C-descriptions](https://extension.colostate.edu/resource/weed-descriptions/) [F-melilotus](https://research.fs.usda.gov/feis/species-reviews/melspp) *Evidence scope: Management synthesis.* ## 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 - **C-floristic-2020** — [Colorado Floristic Quality Assessment: 2020 Update](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf), Colorado Natural Heritage Program, Colorado State University. Accessed 2026-09-07T02:27:33+00:00. Locator: Appendix B, Colorado species list: scientific name and native/non-native fields. - **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-melilotus-officinalis** — [Melilotus officinalis](https://plants.ces.ncsu.edu/plants/melilotus-officinalis/), NC State Extension. Accessed 2026-09-07T02:23:11+00:00. Locator: Description, identification attributes and plant problems; toxicity section where present. - **F-melilotus** — [White and yellow sweetclover](https://research.fs.usda.gov/feis/species-reviews/melspp), USDA Forest Service, Fire Effects Information System. Accessed 2026-09-07T02:26:14+00:00. Locator: Named species or genus; identification, distribution and hazard sections where available. - **C-descriptions** — [Weed descriptions](https://extension.colostate.edu/resource/weed-descriptions/), Colorado State University Extension. Accessed 2026-09-07T00:24:02+00:00. Locator: Species entries. - **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=yellow-sweetclover) — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care. # Appendix for agents Colorado inclusion: [C-floristic-2020](https://cnhp.colostate.edu/download/documents/2020/CO_FQA_2020_Final_Report.pdf), Appendix B; PDF page 63; Melilotus officinalis. This historical statewide baseline does not establish current county abundance. ## 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. ## Identity and evidence boundaries Match the scientific name and synonyms, not the common name alone. 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 | |---|---|---|---|---| | yellow-sweetclover-1 | Identification | Species-specific | N-melilotus-officinalis, F-melilotus | No quantitative safe exposure established here. | | yellow-sweetclover-2 | People | Review limitation | Review limitation | No quantitative safe exposure established here. | | yellow-sweetclover-3 | Dogs & cats | Review limitation | Review limitation | No quantitative safe exposure established here. | | yellow-sweetclover-4 | Other animals | Sweetclover group evidence | F-melilotus | No quantitative safe exposure established here. | | yellow-sweetclover-5 | Plants & habitat | Species-specific | N-melilotus-officinalis | No quantitative safe exposure established here. | | yellow-sweetclover-6 | Management & timing | Management synthesis | C-descriptions, F-melilotus | 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). --- Canonical HTML: https://denson.github.io/colorado-weed-field-guide/plants/yellow-sweetclover/ Content revised: 2026-09-07T02:46:00Z Markdown mirror: https://denson.github.io/colorado-weed-field-guide/plants/yellow-sweetclover/index.md Text fallback: https://denson.github.io/colorado-weed-field-guide/plants/yellow-sweetclover/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